Methods and apparatus for providing realistic medical training

ABSTRACT

Method and apparatus to provide simulation of a human casualty. In one embodiment an autonomous casualty simulator includes a processing module having a scenario progression controller and a physiological modeling system to receive sensor input and to control effectors. The autonomous casualty simulator can be contained in a nominal human mannequin form.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application of and claims thebenefit of International Patent Application PCT/US2006/037663 filed Sep.28, 2006, published in the English Language on Feb. 14, 2008, asWO2008/018889, which application claims benefit from U.S. ProvisionalApplication No. 60/721,848, filed Sep 29, 2005, all of which areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

The Government may have certain rights in the invention pursuant toDepartment of Defense grant DAMD 17-02-2-0006, as amended with fundsfrom Research Area Directorate II/Combat Casualty Care.

BACKGROUND

There a number of known medical simulation systems that are directed toparticular training aspects. One such system is provided by MedicalEducation Technologies Inc.'s (METI, Sarasota, Fla.) known as HPS,directed to high level anesthesia and critical care training system.However, this system lacks portability and stand-alone capabilities. Inaddition, the HPS system does not realistically model trauma except ascardiopulmonary sequelae of hypovolemic states. The METI ECS issemi-portable, and the SAPS is a portable, instructor-initiatedmodel-driven control environment that can be programmed to respondaccording to pre-programmed algorithms or can be manually overridden.

Also known in the art is a system provided by Laerdal Medical AS(Stavanger, Norway) including mannequin systems for first responderbasic first aid resuscitation and Advanced Cardiac Life Supporttraining. These systems lack accurate realism and require line-of-sightand an instructor to operate them. Laerdal also offers a base model(Tuff Terry) consisting of a rigid plastic human form that has notreatment responses to be used for modeling patient transport andextraction. Gaumard Scientific Company, Inc. (Miami, Fla.) produces HALS3000, a mobile, instructor-driven model-based system that can be usedfor anesthesia and life support training in first responder andin-hospital training, however, it also requires line-of-site instructoroperation and is not capable of use in harsh environmental conditions.

In the civilian world, many technical and medical specialties care fortrauma victims, including Emergency Medical Technicians (EMTs),paramedics, police officers, fire and rescue teams, HAZMAT teams,nurses, surgeons, and emergency physicians. Homeland Security personnel,including those involved with mass casualty training, CBRNE eventscenarios, community disaster teams and other emergency first respondersmust also be trained in emergency management and mass casualty skills.Training these specialists typically involves some interaction with asimulator. The civilian sector relies on training that includes acombination of simulated patients and real cases to provide the breadthof experience needed to be competent in providing medical care.

Medical simulation systems can be found in situations ranging from totalteam training, to individual procedure simulators, to basic skillsdevelopment simulators. A system which encourages medic responsibilityand allows for transfer-of-care enables a higher level of total teamtraining. Recertification and reevaluation occur throughout thepractitioner's career at regular intervals to ensure the care providedis based on up-to-date standards, and oftentimes to refresh skills.

It is believed that the three leading causes of preventable battlefielddeath are extremity hemorrhage, tension pneumothorax and airwaycomplications. The leading causes of death because of combat wounds are:

-   -   Penetrating trauma: 31%    -   Uncorrectable chest trauma: 25%    -   Potentially correctable torso trauma: 10%    -   Exsanguination from extremity wounds: 9%    -   Mutilating blast trauma: 7%    -   Tension pneumothorax: 5%    -   Airway complications: 1%        Improvements in the training of the soldier medic could improve        the killed in action (KIA) rates by 15-20%. Suggested critical        tasks for medics to learn to higher proficiency include:    -   Conducting a rapid patient primary survey (Airway, Breathing,        Circulation);    -   Inserting a nasopharyngeal airway and placing the casualty in        the recovery position;    -   Treating life threatening chest injuries with occlusive        dressings and being able to perform a needle decompression; and,    -   Controlling external hemorrhage.

Another recent development within the Army is the advent of the CLS(Combat Life Saver) program. The CLS course was established to providefor immediate, far-forward medical care on a widely dispersedbattlefield while awaiting further medical treatment and evacuation. Theproponent for the CLS course, the US Army Medical Department Center andSchool (AMEDDC&S), recently updated the CLS course to include skillsthat were recommended from lessons learned in Operations Iraqi Freedomand Enduring Freedom. These revisions include instruction in:

-   -   Decision-making skills for treating a casualty when under fire,        when not under fire, and during casualty evacuation (tactical        combat casualty care or TC3).    -   Use of the emergency trauma dressing (ETD; a.k.a. Israeli        Bandage), an improvement from the old field dressing. The ETD        contains elastic ties that ensure the ability to create a        functional pressure dressing.    -   Use of the combat-application tourniquet (CAT), an improvement        from the cravat-and-stick tourniquet. The CAT has self-contained        components and can be applied with one hand.    -   Insertion of the nasal airway for treating a casualty with        facial injuries or profound levels of unconsciousness.    -   Use of a large-bore needle to relieve air from a casualty's        chest cavity when a chest wound, with collapsed lung, causes        cardiovascular compromise (a tension pneumothorax).    -   Employment of the SKED litter, a kind of rigid plastic        wrap-around litter that can be carried or dragged.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary embodiments contained herein will be more fully understoodfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1. is a top level schematic depiction of an overall architecture ofan autonomous casualty simulator in accordance with an exemplaryembodiment of the invention;

FIG. 2. is a graphical depiction of an encoding relationship between anindependent variable (BV %(t)) and several dependent variables (HR, SBP,DBP, PP, RR, UO).

FIG. 3. is an exemplary a state space lookup table methodology forrobust, real-time modeling and computation of physiological responses.

FIG. 4. is a flow diagram showing an exemplary process for generatingreal-time physiological response using pre-computed response curves.

FIG. 5. is a graphical depiction of exemplary response curves forphysiological variables generated by the Heldt model, where variation ofheart rate, systolic arterial blood pressure and diastolic arterialblood pressure is shown for a 1500 ml drop in blood volume beginning att=0 and extending over 20 minutes.

FIG. 6. is a schematic illustration of an exemplary hydraulic layout forarterial and venous systems as well as the pneumatic systems for pleuralspace pressurization and articulation of a neck for the system of FIG.1.

FIG. 7. is a pictorial representation of an exemplary trauma module limbskeleton of an arm as well as soft tissue and hemorrhage module layout.

FIG. 8. is an assembly rendering of a common trauma module connectionincluding fluid, data, power, and mechanical connectors.

FIG. 9. is a schematic representation of a tourniquet pressure sensingsystem.

FIG. 10. is a pictorial representation of a fluidic pulse generator.

FIG. 11. is a pictorial representation of an electromechanical pulsegenerator.

FIG. 12. is a pictorial representation of a chest wall compliance andCPR detection system.

FIG. 13. is a schematic depiction of a hemopneumothorax chest portal.

FIG. 14. is a schematic representation of a an assembly and pupillaryresponse system.

FIG. 15. is a frontal pictorial view of a skeletal chassis and nestedtorso components.

FIG. 16. is a lateral view of a skeletal chassis and nested torsocomponents.

FIG. 17. is a front view of a skull and cervical spine mechanism.

FIG. 18. is a lateral view of a skull and cervical spine mechanism.

FIG. 19. is a left side perspective view of a pan-tilt mechanisms.

FIG. 20. is a right side perspective view of a pan-tilt mechanisms.

FIG. 21. is a perspective view of a flexible neck segment includingangular motion limiter geometry.

FIG. 22. is an exploded perspective view of a flexible neck segmentincluding angular motion limiter geometry.

FIG. 23. is a pictorial representation of a shoulder wishbone assemblyand damper systems.

FIG. 24. is an exploded perspective view of a scapula assembly includingconsciousness controls.

FIG. 25. is a pictorial representation of a battery pack including waterresistant connectors and external waterproof encasement and a rechargingsystem with battery packs fully and partially-inserted.

FIG. 26. is a schematic representation of a control panel.

DETAILED DESCRIPTION

The present invention provides methods and apparatus for simulating ahuman casualty where mechanisms, power sources, and process controls areself-contained within the shape and volume of a nominally-sized humanform allowing a person to locate, diagnose, treat, observe a change incondition of, and transport the simulated casualty, outside of theline-of-sight of an instructor and without the necessity of someoneoperating the simulator. This autonomous systems design places the medicat the center of a sensor-processor-effector loop.

FIG. 1 shows an exemplary system 100 having a central processor module102 having a physiological modeling system 104 coupled to a scenarioprogression controller 106. The physiological modeling system 104 caninclude a controller 108 to receive sensor data 10 for diagnosticassessment and control effectors 112 to provide simulated physiologicalresponses, as described in detail below. In one embodiment, thecontroller 108 is implemented in a field programmable gate array (FPGA).

In general, sensors 110 detect and measure the medic's diagnostic andtreatment procedures, the controller 108 computes physiologicalresponses based on pre-programmed physiological models, and effectors112 display clinical signs and responses back to the medic. The medic“closes the loop”: medic decisions and actions directly determine thefate of the simulated casualty. To achieve this high level ofself-contained patient simulation, an embedded real-time centralcomputer processor autonomously controls the system.

In an exemplary embodiment, the system is self-contained. As usedherein, self-contained means that the elements needed to effectphysiological simulation during use are contained within the mannequin.The term self-contained does not preclude communication, such aswireless communication/control, with the system, such as by aninstructor.

Before describing the invention in detail, some general information onthe invention system is provided. Invention embodiments are referred toas an Autonomous Casualty Simulator (ACS). This is not intended to belimiting, but rather, to convey a general concept for the illustrativeembodiments contained herein. In one embodiment, the Autonomous CasualtySimulator (ACS) is the height and weight of a nominal adult male(approximately 72″ tall and 190 lbs). In one embodiment, the structuralsystem is an articulated skeletal chassis, which is accurately jointedto enable mobility and range of motion similar to a real human skeleton.Covering the skeleton and the internal mechanical and computationalcomponents of the ACS is a modeled representation of the relevantmuscles and skin covering needed to accurately depict the outerstructure of an adult male. The user preconfigures the system foroperation by setting controls on the ACS Control Panel 118 located onthe lower back of the chassis. The scenario progression controller 106(FIG. 1) generates a sequence of trauma events (hemorrhage, airwayconstriction, hemothorax, etc.) resulting in the high-fidelitysimulation of a particular trauma case. The central processor 102 logsand timestamps data, including vital signs, medic radio frequencyidentification (RFID) and global positioning system (GPS) coordinates.The ACS unit also can communicate with an instructor remote monitor 120via a wireless radio frequency (RF) link 122.

One characteristic of the ACS system is responsiveness. The ACS canprovide an interactive experience to the medical trainee by activelysensing (1) applied interventions; and, (2) its own internalphysiological state. This is achieved by incorporating a set of sensorsthat communicate with the central programmable controller. Sensors areincluded to monitor medic actions and interventions including but notlimited to: identifying the trainee (via RFID tags), measuringintravenous (IV) fluid input, tourniquet pressure, location of needleinsertion and depth of insertion during needle thoracotomy to relievetension pneumothorax, sternal displacement (during administration ofcardiopulmonary resuscitation (CPR)), head acceleration and cervicalspine angle.) Additionally, sensors can be included to measurephysiological variables including but not limited to: blood volume,hemodilution, and bronchial air flow. Additional sensors provide data onsystem parameters such as battery charge level and internal temperature.This list of sensors and variables sensed is representative, but is notnecessarily exclusive of other sensors and variables.

A range of effectors generates both general clinical signs and specifictrauma clinical signs as well as other responsive behaviors. Physiologicsigns are produced by effectors, such as electromechanical actuators, togenerate palpable peripheral pulses and drivers for lung expansion andcontraction. Specific trauma states are produced by effectors such asvalves to admit blood or air into the pleural space and peripheral bloodflow controllers to produce pulsatile flow of blood out of a laceratedartery. Additional responsive behaviors are produced by effectors suchas motors to turn the head in the direction of a voice and an amplifiedspeaker to produce voice, vocalizations of pain and sounds of laboredbreathing.

Self-Contained, Autonomous Functionality in Humanoid Form Factor

In one aspect of the invention, ACS functionality, including itsmechanisms, sensors, actuators, power sources and automatic controlsystems, so as to fit within the size and shape constraints of arealistic, nominal human form.

It is understood that the term “nominal” refers to a range within plusor minus two standard deviations of the average height, weight andvolume of the age- and gender-matched human that the ACS is designed tosimulate. This is equivalent to approximately the central 95% of thedistribution for height, weight and volume.

In one embodiment for the ACS, the target human is an adult male, withheight 72″ (1.83 m) and weight 190 lbs. (86.4 kg). The volume of a malehuman with this size and weight is approximately 2.8 cubic feet (0.079m³). In one embodiment, the entirety of the structural, computing,sensing, actuating, fluidics, power and communications elements havebeen designed to fit within this very limited volume. Furthermore, allapparatus must meet the even more restrictive constraint of fittingwithin this volume as embodied in the morphology of a human body, withcorrect external anatomic form and proportions of the head, neck, torsoand limbs.

Computer Control System

As described above in FIG. 1, in an exemplary embodiment the ACS iscontrolled by an onboard computer system that is based on a two-partarchitecture: a real-time central processor 102 and a field-programmablegate array (FPGA) 108. This combination allows a lower speed—andtherefore lower power and lower heat—Pentium II class processor tohandle overall control, communications, and data logging, while the FPGAinterfaces directly to the sensors and effectors, offloading low-leveldata acquisition and processing tasks from the central processor andproviding the advantage of the high-speed parallel processing powerafforded by FPGA technology. In an exemplary embodiment, the algorithmsand models of physiology are implemented across both the real-timeprocessor (for more mathematically complex functions) and the FPGA (forsimpler, faster, more “reflexive” responses.) This partitioning offunction may be regarded as analogous to that found in the human centralnervous system, with the central processor providing the higher-levelcomputation and communication abilities of the brain and the FPGAproviding the fast, reflexive responses and peripheral sensory-effectorintegration of the spinal cord.

Computational Architecture: Real-Time Processor, Real-Time OperatingSystem and Field-Programmable Gate Array (FPGA)

In an exemplary embodiment, the central programmable processor (computercontroller) is specified to be rugged, compact, shock and temperaturetolerant, have a real-time clock (for data logging) and use flash memoryrather than a hard drive to eliminate fragile moving parts susceptibleto drop and impact shock. One embodiment employs the use of a real-timeoperating system (RTOS) on the central processor because of the greaterreliability and immunity to crashing afforded by an RTOS that isdesigned specifically for embedded, unattended control applicationsoften in mission-critical environments such as the central controlcomputer of an automobile or avionics system.

One embodiment incorporates a Field-Programmable Gate Array (FPGA) toimplement physiology, sensor and actuator processing algorithms directlyin silicon. (An alternative embodiment could implement these algorithmsin a custom-built Application Specific Integrated Circuit (ASIC).) Thisprovides extremely fast processing and very high resistance to softwarecrashes, since algorithms executing on an FPGA are effectivelyhard-wired circuits that function independently of and in parallel witheach other and with any external operating system. These algorithms arethus immune to conventional system crashes and interruptions.

An RTOS is typically much more compact than a standard operating system(such as Microsoft's Windows XP) and therefore also offers the advantageof fast booting (typically on the order of one second). This ensuresthat the system is ready for use soon after it is turned on andmaximizes the productive use of instructors' and trainees' time. Boththe RTOS and the FPGA also offer tight control of input-output timing, acritical requirement for a system such as ACS with a large number ofsensors and actuators. (An RTOS, by definition, provides real-timedeterministic control with guaranteed bounds on response latency. Thisis distinctly different than a conventional operating system, where manyactions such as disk reads or network activity can interrupt I/Oprocessing, causing unexpected and random delays.) For example, tightcontrol of timing signals to a pulse actuator ensures that a prescribedsteady pulse is actually actuated at a constant rate and is perceived bythe trainee as a regular rhythm. Unbounded interrupts generated in acentral processor with a conventional operating system architecturecould produce a pause or irregularity in the pulse actuator's action,and this could be falsely interpreted by the trainee as having clinicalsignificance.

Another embodiment uses a state-space model to represent the sequence ofevents specified by the configuration of the controls on the ACS ControlPanel. State-space models are used as the framework for building robust,maintainable applications since they can represent complex,interdependent systems in simple, graphical terms. Lower-levelprocessing of sensor inputs and effector outputs, including “reflexive”responses (such as pupil response to light) are executed directly on theFPGA. Overall system control, timing, communications and data-loggingfunctions are programmed to run on the real-time central processorexecuting under the RTOS.

Another embodiment employs an algorithmic architecture termed the statespace-multidimensional lookup table methodology to provide a means ofgenerating complex physiological responses that is both flexible androbust. This will be described in detail below.

Data Logging

One embodiment uses an onboard flash drive to provide non-volatile datastorage in a rugged, shockproof medium. Assuming a maximum data loggingrate of 1 Hz, approximately 1 MB of storage is required per hour of datalogged. Approximately 300 bytes of storage will be required to holdlogged variables for each time point, including, but not limited to:

-   -   Vital signs        -   Heart rate        -   Heart rhythm        -   Respiratory rate        -   Respiratory depth        -   Systolic blood pressure        -   Diastolic blood pressure        -   Level of consciousness    -   Sensor data        -   Cervical spine angle        -   Head acceleration        -   Arm tourniquet pressure        -   Leg tourniquet pressure        -   Left and right intrathoracic pressure (for tension            pneumothorax events)        -   Left and right main bronchus airflow        -   Total blood volume        -   Administered fluid volume        -   Core body temperature    -   Times of occurrence of programmed or automated trauma events        -   Initiation of limb hemorrhage        -   Pneumothorax        -   Tension pneumothorax        -   Hemothorax        -   Airway obstruction        -   Shock        -   Seizure        -   Medic RF-ID        -   GPS coordinates        -   Time-of-day stamp            Continuous binaural digital audio signal recorded from the            ear canal microphones can be compressed using the MPEG-1            layer III (mp3) codec at a rate of 96 kbps with variable bit            rate encoding, sufficient for excellent fidelity for voice            recordings. The resulting compressed data stream requires            approximately 43 MB per hour of recorded audio.            Physiological Systems Modeling

One aspect of the ACS invention provides continuous physiology: in oneembodiment ACS is built around trauma-relevant physiological systems andresponses, and these systems respond continuously and realisticallythroughout a training scenario—e.g., ACS will “die”, spontaneously andwithout instructor input, if effective care is not given to it. Thisapproach ensures that trainees learn that ongoing assessment andtreatment is crucial to patient survivability: continuous physiologywill require ongoing assessment and continuous responsibility.

In one embodiment, the models used are based on empirically observed andmeasured human physiological responses to various physiologicalchallenges such as hemorrhage or airway occlusion. These empirical datamay be derived from a plurality of sources, including clinicallyobserved data used as the basis for accepted standards of traumaphysiology and care, such as the “gold standards” as codified in theAdvanced Trauma Life Support Program Manual (American College ofSurgeons, 6th ed., 1997) and the Special Operations Forces MedicalHandbook (Yevich, Whitlock, Broadhurst et al., 2001). The empirical datamay also be derived from experimental science, such as the lower-bodynegative pressure (LBNP) model of human physiological responses to bloodloss. The empirical data may also be derived from quantitative datarecords obtained from trauma patients, for example, while they areattended by medical personnel and connected to physiological monitoringinstrumentation during treatment and transport.

In another embodiment, the physiological models used may additionallyincorporate validated data generated by quantitative and computationalmodels of cardiovascular physiology; in particular, one embodimentutilized the physiological models developed Heldt, 2004 and Heldt,Chang, Verghese and Mark, 2003. In one embodiment, as needed, basedphysiological responses on the Guyton model of fluid and circulatoryregulation (Guyton, Coleman and Granger, 1972; Guyton, Coleman, Cowleyet. al, 1972) and models specifically developed to run in real-time forteaching cardiovascular physiology (Davis 1991; Davis and Mark, 1990;Campbell, Zeglen, Kagehiro and Rigas, 1982; Sah and Moody, 1985).

It is understood that any of these embodiments may additionallyincorporate practical advice from emergency medicine physicians, traumaspecialists and military physicians and medics. By tuning the modelswith heuristics derived from the experience of these trauma experts wecreated a system that does not merely respond “by the book”, but toevery extent that is practicable matches the responses seen in real-lifein the field.

The models of Heldt et al. provide an understanding of cardiovascularresponses to orthostatic stressors. The Heldt model is a very large(over 100 parameters), computationally intensive model that offersexquisite detail in modeling the cardiovascular system and its responseto external stressors, but is not suitable for execution in real-time.One aspect of the current invention is a process for leveraging thiswork to develop simplified and computationally efficient models ofcardiovascular dynamics that, despite their simplicity, capture thedynamics of trauma-relevant physiological responses and can be executedin real-time and with high reliability on the ACS central computer. Thisenables the ability, for example, to provide real-time responses in ACSto changing variables such as blood volume during the simulation ofexsanguinating hemorrhage.

Architecture, Algorithms and Process to Imiplement Physiological Modelsand Automatic Control

Another embodiment describes and includes the process to meet the needfor autonomous control and accurate physiological modeling in ACS bymeans of a compact, computationally efficient implementation ofalgorithms that can run in real-time on the embedded real-time processorand FPGA.

In one embodiment, the real-time physiological models and controlalgorithms running on the central processor architecture are implementedby a combination of state-space and multidimensional lookup tabletechniques, supplemented where needed by solvers for low-order(primarily 1st and 2nd order) differential equations. State-spacemethodology is employed to simulate principal physiological and clinicalstates, and to incorporate time-dependent and behavior in the models. Inan exemplary embodiment, the physiological state at any given time is afunction of five parameters:

-   -   1. The specific trauma event sequence specified to occur by the        instructor.    -   2. Current time relative to the trauma event sequence.    -   3. Current sensor inputs values.    -   4. Current physiological status values (a function of the        present state and the sensor inputs).    -   5. The preceding state history.        Within a given state, a set of multidimensional lookup tables        relates input (independent) and output (dependent) variables.        Typically, input variables are derived from sensor signals in        the system, and reflect some physical variable that is affected        by treatment of the simulated patient. Example input variables        are total blood volume, administered IV fluid volume and        bronchial air flow rate. Output variable examples are cardinal        physiological status values, such as heart rate and blood        pressure. Output variables are used to generate signals that        control vital sign effectors in the system, such as pulse        effectors and hemorrhage effectors.

An example lookup table is shown in Table 1. This lookup table relatesthe independent variable of Total Blood Volume to the output variablesHeart Rate, Systolic Blood Pressure, Diastolic Blood Pressure, PulsePressure, Respiratory Rate, Urine Output and Mental Status. Note thatthe data provided in this table are representative data.

TABLE 1 Example lookup table relating the input variable Total BloodVolume to eight different output variables - representative data onlyATLS Class 1 Class 2 Class 3 Hemorrhage Up to 15 to 30 to 40% Class 4Category Baseline 15% loss 30% loss loss >40% loss Total Blood 100 85 7060 50 40 35 0 Volume Class Endpoints (%) Heart Rate 80 100 120 140 160180 0 0 (bpm) Systolic BP 120 120 120 100 80 60 0 0 (mm Hg) Diastolic BP80 80 90 80 70 60 0 0 (mm Hg) Pulse Pressure 40 40 30 20 10 0 0 0 (mmHg) Respiratory 20 20 30 40 40 40 0 0 Rate (rpm) Urine Output 30 30 20 50 0 0 0 (mL/hr) CNS/Mental Baseline Anxiety 1 Anxiety 2 Anxious,Lethargic, Unconscious Unconscious/ Unconscious/ status ConfusedConfused Dead Dead

The lookup table functions within the system as follows. During ahemorrhage simulation, the blood fluid flow sensor measures the rate offlow of blood simulant. The central programmable processor totals theflow measurements to generate a measure of total blood lost. We definethe following variables:

-   -   B{dot over (V)}e(t) is the rate of blood emitted (lost) at time        t, as measured by the blood fluid flow sensor    -   BVe(t) is the total blood emitted (lost) by the system at time t    -   BV₀ is the initial total blood volume    -   BV(t) is the total blood volume at time t    -   BV %(t) is the blood volume percentage at time t (percent of        initial total blood volume)        ATLS refers to the Advanced Trauma Life Support Manual and the        trauma treatment guidelines contained therein, published by the        American College of Surgeons Committee on Trauma. 6^(th)        ed., 1997. Note that here and in what follows the term “blood”        may be used as a compact term for “blood simulant”. It is to be        understood that any references to the term “blood” as used in        respect to the ACS do not refer to actual human blood, but        rather a liquid used to simulate relevant perceptual attributes        of actual blood, such as its liquidity and color

We further define that time t=0 is the instructor-defined start time ofa particular instance of a particular simulation training scenario.

Then:

${{BVe}(t)} = {\int_{0}^{t}{B\;\overset{.}{V}{e(\tau)}{\mathbb{d}\tau}}}$for the embodiment in which the blood fluid flow sensor provides asoutput a continuous (e.g., analog) signal proportional to flow rate.Alternatively:

${{BVe}(t)} = {\sum\limits_{i = 0}^{t = N}{B\;\overset{.}{V}{e(i)}}}$for the embodiment in which the blood fluid flow sensor provides asoutput a discrete (digital) pulse signal, the pulse rate beingproportional to flow rate. In this case N is the total number of pulsesoutput between the start time and the current time t.

The central programmable processor then executes the followingcomputation to determine the total blood volume percentage at time t:

${{BV}\;\%(t)} = {\frac{{BV}_{0} - {{BVe}(t)}}{{BV}_{0}} \times 100\%}$The independent variable BV %(t) is then applied as an index variable tothe data in Table 1; corresponding values of the output variables aredetermined by interpolation between given data points. This isillustrated in the graph 200 in FIG. 2, in which the input variable BV%(t) is assigned to the abscissa and the output variables are assignedto the ordinate of the graph.

The output variables at time t may then be employed in computations ofadditional physiological parameters. The output variables, or functionsof them, may also be employed as control signals (after appropriateconversion to analog or digital electronic signals) for actuators suchas, for example, pulse effectors, respiratory motion actuators or audiogenerators of heart sounds.

In the above example a one-dimensional lookup table is employed torelate one input variable to one output variable. The relationshipbetween physiological variables in ACS will typically be more complex,with an output variable being a function of two or more inputvariables., and the lookup table technique can be extended to embodyrelationships between variables in which the value of an output variabledepends on two or more input variables. In the general n-dimensionalcase, an output variable is a function of n input variables. Thisrelationship can be programmatically represented by an n-dimensionallookup table, typically implemented as an n-dimensional array of datapoints in the memory of the central processor.

For example, level of consciousness (LOC) is a function of systolicarterial pressure (SAP) and blood oxygenation (% SpO₂), as well as thecurrent neurological state. Blood oxygenation is, in turn, a function ofhematocrit (HC7) and total bronchial airflow rate AV_(T) ^(Y). Thus, LOCcan be expressed:LOC=f₁(SAP, f₂(HCT, A{dot over (V)}_(T)))f₁ and f₂ are each implemented as two-dimensional lookup tables, each ofwhich can be viewed mathematically as a surface above a two-dimensionaldomain. Changes in input values move the output values to new locationson this surface. The technique extrapolates to higher dimensions, wheren-dimensional lookup tables implement hypersurfaces above n-dimensionalranges.

The use of multidimensional lookup tables to embody the relationshipsbetween key physiological variables is a key enabling methodology.Replacing complex, high-order differential equation (DEQ) models withlookup tables enables real-time performance and increases stability andreliability, particularly for a system subject to nondeterministic humaninputs (i.e., the medical trainee's interventions) since DEQ solvershave the potential to diverge (i.e., “crash”) for extreme orunanticipated out-of-bounds values (or combinations of values) of inputvariables and parameters.

The combination of state space methodology and multidimensional lookuptables provides a means of generating complex physiological responsesthat is both flexible and robust. In cases where an output variabledepends not just on the current value of one or more input variables butalso on the past history of those variables, a series of states can beemployed to approximate this history-dependent behavior. The history ofone or more input variables determines which of a plurality of possiblestates is the current state, and each state has associated with it aparticular lookup table relating input and output variables for thatstate. Thus the relationship of the output variables to the inputvariables can vary depending on the time history of the input variables.

For example, in the hemorrhage example above, if the total blood volumepercentage reached a value of 40% or less, brain and heart tissues wouldbe significantly hypoperfused and experience severe hypoxia. Withinapproximately 5 minutes, there would be irreversible loss of brain andheart function. At this point, administration of IV fluid or otherresuscitative measures would be ineffective—they would not produce thesame input-output variable behavior as they would have if administeredearlier in the time course of the scenario. This time-dependent behaviorcan be implemented using the state space and lookup table methodologydescribed herein.

For an example, referring to FIG. 3. At the start of the scenario State1 300 is entered. State 1 300 has associated with it Lookup Table 1which is used to relate input and output variables. (Lookup Table 1could, for example, be based on the input-output variable relationshipspresented above in Table 1.) At a regularly recurring interval the totalblood volume percentage variable is tested 302 to see if it has fallenbelow 40%. If yes, a timer variable, T₄₀, whose value is the elapsedtime that the total blood volume percentage is under 40%, is tested 304at a regularly recurring interval to determine if it exceeds 5 minutes.If yes, a new physiological state, State 2 306, is entered. State 2 nowhas associated with it Lookup Table 2 which encodes a different set ofinput-output variable relationships than Lookup Table 1. For example,Lookup Table 2 could specify that all output variables have the constantvalue 0, representing the irrecoverable cessation of vital signs(death).

This is a simplified example to illustrate some features of the statespace-multidimensional lookup table methodology. In practice, the testsfor state transitions may be quite complex, involving multiple ranges ofthe test variables or test variables that are functions of inputvariables, output variables and time.

The use of state space methodology combined with lookup tables to relateinput and output variables enables the incorporation of real-world humanphysiological response data (from sources such as described above)directly into a simulated trauma scenario. If, for example, a patientwho was attached to vital signs monitoring instrumentation developed atension pneumothorax in the field and was treated, the data record fromthis event (obtained subject to pertinent guidelines regarding consentand confidentiality) could be incorporated into a set of lookup tablesin the ACS that would generate in the simulation exactly the sameresponses as occurred during the evolution of the actual clinical case.

In cases where empirical data on the human physiological responses tospecific courses of trauma and its treatment is sparse or unavailable,the data informing the state space structure and lookup tables can bederived from quantitative computational models of human physiology. Theessence of this process is to run the quantitative physiological model,which may be complex and computationally intensive, off-line (that is,on a higher-powered computer external to the ACS system) for a range ofindependent variables and parameters in order to obtain data thatcaptures the relationship between the variables of interest. Thismodeling is physiologically realistic but time-consuming; for example itmay require on the order of several minutes per model run each time aset of input parameters is changed. These generated data are thenemployed to create multidimensional lookup tables that can beimplemented in the FPGA. Changes in sensor inputs to ACS (blood volume,bronchial air flow) are interpreted by the lookup tables and causecorresponding changes in the vital signs and output effector responses.The physiology is effectively encoded in the lookup tables, which,unlike the original model, are compact and fast.

The state space-multidimensional lookup table methodology may be used torepresent highly nonlinear physiological system behavior. Representationto within desired bounds on accuracy over a wide range of systembehavior may be obtained by creating a sufficient number of states suchthat system behavior within each state is adequately approximated by theassociated lookup table. Each state is defined so as to encompass alimited regime of system behavior, and when system variables reach thelimits of a regime, a transition to a new state occurs. This process issomewhat analogous to the piecewise linearization of a nonlinearfunction for local analysis, where a local approximation is used topermit analysis that otherwise would be intractable. The approach alsois analogous to the technique of gain scheduling in control systems,wherein different control functions are defined for different ranges ofthe system variables.

As a specific example of translating the physiological behavior of acomputational model to a lookup table that relates input variables tooutput variables, we illustrate a process 400 in FIG. 4 for onecomponent of physiological repertoire: the response of heart rate andblood pressure to hemorrhage. Starting at the top of the figure, adesired set of independent and dependent physiological variables ischosen for modeling. In this example, to determine the responses ofheart rate (HR) and arterial blood pressure (BP) to hemorrhage, theindependent variable are specified to be total blood volume (TBV) andthe dependent variables are heart rate (HR) and systolic and diastolicarterial blood pressure (SAP and DAP). A function is specified thatdecreases blood volume with time and the model is run to determine theoutput curves for HR, SAP and DAP.

FIG. 5 shows an example of the data curves produced by the Heldt model.The solid curve 500 is total blood volume: initially, TBV is 5000 ml, anominal value for a 70 kg male. At time t=0, a severe hemorrhage ismodeled by specifying TBV to decrease by 1500 ml over the course ofapproximately 20 minutes. The Heldt model then computes thecorresponding changes in HR 502, SAP 504 and DAP 506, which are alsoshown on the graph. These curves are encoded (by a computer external tothe ACS) into lookup table data that enable the input variable TBV to bemapped to the output variables HR, SAP and DAP. These lookup tables arecoded in the FPGA for fast, real-time computation.

There are limits to the accuracy of any computational model and,especially with extreme perturbations to physiological variables, realphysiological responses may not be fully captured and predicted by onemodel. An example is cardiovascular system behavior as exsanguinationproceeds to the point of death, where the rise in heart rate willultimately convert to a precipitous decline. For obvious reasons,deliberate experimental validation of a cardiovascular model in humansis not possible for this condition. However, quantitative data doesexist for other animals and qualitative data exists based on theobservations of clinicians treating trauma patients. For example, thedrop in heart rate with severe exsanguination is due to a mechanismknown as the Bezold-Jarisch reflex and this has been qualitatively andquantitatively described in published literature, such cases we willextend the data curves generated by the Heldt model (or other models)with additional data from validated sources so the full range ofphysiological response needed is available. The use of lookup tablesfacilitates this process, since response curves from different modelscan be spliced together to cover the entire desired range of variationof an independent variable. Specific models can be chosen to coversubranges for which each model is optimally suited. The result is anaccurate model of physiological responses that any one model may beincapable of providing.

As the requisite lookup table is coded in the FPGA, the ACS system canrespond realistically to a simulated hemorrhage scenario. As shown inthe bottom left of FIG. 4, for example, during a hemorrhage scenario aninternal sensor measures the hemorrhage flow rate, from which theremaining volume in the internal blood reservoir can be calculated. Thissensor data is read into the FPGA and after numerical integration, ismapped to HR and BP via the lookup table. The HR and BP variables arestate variables that provide a window into the overall health of thesimulated patient as well as provide the appropriate physiologicresponse. As shown in FIG. 4, these variables can be relayed to theinstructor remote monitor 120 (FIG. 1) for real-time display and arerecorded in the onboard data log with a time stamp.

Further, the HR and BP variables are displayed to the trainee throughsimulated clinical physical signs generated by effectors. For example,HR will set the rate of the pulse effectors in the carotid, brachial,radial and femoral arteries, and will likewise set the frequency ofpulsatile flow in a bleeding artery by controlling the rate of openingof the arterial fluid flow valve. BP will be used to set the strength ofthe pulse effectors and will also influence the amplitude of thearterial flow. The relationship of BP to pulse strength is setindividually for each pulse site—for example, peripheral pulses in theradial arteries cannot be felt when SAP drops below roughly 80 mm Hg,and this same effect will be replicated in ACS by turning off the radialpulse effectors when the computed SAP drops below 80 mm Hg.

Specific Physiological System Functions

In one embodiment, the architecture of the physiological modeling systemis broadly divided into three main subsystems: cardiovascular,respiratory and neurological. Functions to be modeled and implemented ineach of these subsystems are described below.

Cardiovascular System Model

In one embodiment, the central physiology processor computes cardiacrate and rhythm, and systolic and diastolic blood pressures. Total bloodvolume is sensed and the central physiology processor responds withrealistic changes in cardiac rate, blood pressure, respiratory signs andlevel of consciousness. Bronchial airflow is sensed and the centralphysiology processor responds with appropriate changes in cardiac rateand blood pressure. Pulse rate and strength are determined by cardiacrate and systolic blood pressure. If systolic blood pressure drops belowa critical threshold, peripheral pulses disappear. The rate and volumeof hemorrhage is controlled based on cardiac rate and systemic bloodpressure. The volume of administered IV fluid is sensed and is avariable that influences the computation of cardiac rate and bloodpressure (and, through the respiratory and neurological systemsdependencies on these variables, administered fluid also affectsrespiratory responses and level of consciousness.) Hemodilution iscomputed from sensor measurements of total blood volume and administeredfluid volume. Hemodilution is monitored by the central physiologyprocessor, which responds with realistic changes in cardiac andrespiratory signs and level of consciousness. Cardiac arrest can beprogrammed to occur at a specified time, as well as whether arrestresponds to resuscitation and, if so, the duration of arrest untilresponse (assuming effective intervention by the medic). Cardiac arrestmay also be generated automatically by the physiological modeling systemsufficient if sufficient deterioration occurs in the simulated patient'scardiovascular status.

Extremity Trauma Modules

In one embodiment, the torso of the ACS system becomes a platform for avariety of unique trauma modules to connect to. Depending on thespecific training goals, individual ACS units can be customized byconnecting the arm and leg modules in a configuration to match thetraining objectives. The connection provides transport and return of,but is not limited to: blood, IV fluid, power, and data.

In another embodiment, the individual trauma module contains a piece ofhardware such as a USB key, flash drive, or other form of non-volatilememory which can be preloaded with the control mechanisms necessary torun the mechanics and electronics contained on the attached limb. Thehardware would communicate with the central processor via a commonApplication Programming Interface (API) for control purposes and enablerelevant common ACS data logging. This allows for more advanced modules,such as an ultra-realistic femur fracture management limb, to work withthe same ACS torso which accepts a low-cost plastic limb without pulsesor hemorrhage capability for use in extraction-only exercises.

A further embodiment describes a hemorrhage control system with eachremovable limb module having the following features:

-   -   Strong common structural connection    -   Simple locking release mechanism    -   Presence indicator switch to tell the central processor that the        device is attached or detached    -   Method of informing the system which module is connected

A further embodiment describes a hemorrhage control system with eachremovable limb module supporting the following features:

-   -   Anatomically correct weight    -   High-pressure arterial flow    -   Low-pressure venous flow    -   Soft-tissue hemorrhaging    -   Protruding bone    -   Bone marrow seepage    -   Position sensor to monitor relative orientation to the master        unit    -   Durable skin covering    -   Realistic muscle and fat layers

A series of different limb modules could be part of the system, allowingthe presentation to the trainee either healthy, undamaged limbs, orlimbs with various injuries, up to and including full traumaticamputation. The upper extremity limb modules could include:

-   -   Healthy upper arm from slightly below the shoulder to slightly        below the elbow, including the elbow joint    -   Blast/gunshot injury to upper arm, including the components        described above, but with an open wound and visible damage to        the humerus    -   Full arm blow-off above the elbow, which will include only the        upper arm down to the location of the blow-off.    -   Healthy lower arm, from below the elbow through to the hand    -   Blast/gunshot injury to lower arm, including moulaged open wound    -   Full lower arm blow-off above the wrist

Lower extremity modules could include:

-   -   Healthy upper leg from below the hip joint to below the knee        joint    -   Fractured femur module, with closed fracture and mechanisms for        generating simulated compartment syndrome    -   Traumatic amputation above the knee, including only a stump    -   Healthy lower leg, from below the knee and including the foot    -   Blast/gunshot injury to the lower leg, including moulaged open        wound    -   Full lower leg blow-off below the knee with accompanying foot        module for limb salvage complications.

In one embodiment, the limb trauma module connection points will belocated in the upper half of the humerus and in the upper part of thefemur. Another embodiment includes connections just below the elbow andjust below the knee for lower extremity trauma modules to be connected.Each connection point will include reinforced and rigid mechanicallatches to hold the components above and below that point together;quick release fluid connectors with integral shut-off valves to carryblood simulant to the sites of injury and IV fluid from venous accesslocations, and other fluids as appropriate (e.g. fluid to pressurizecompartment syndrome thigh elements); ruggedized electrical connectorsto send control signals to electrically actuated pulsation units andreceive data from pressure sensors in each.

Each connection point includes a release mechanism that frees the limbsegment upon deliberate manipulation of a push-button-like element. Thepush-button is offset beneath the surface of the limb segment, andprotected from inadvertent activation.

The exposed bone and soft tissue damage are anatomically correct andhave realistic appearance.

Hemorrhage Generation & Control System

One aspect of the trauma training system is the system's capacity tobleed and have its bleeding controlled through proper application ofdirect pressure, tourniquets or other techniques for hemostasis. The ACScontains a replaceable supply of blood simulant, a system to pressurizethe blood and a series of valves which direct the flow of blood simulantto the sites of bleeding. Further, these valves can be controlled suchthat by their controlled opening and closing, pulsatile bleeding (e.g.arterial spurting) can be generated. In addition, pressure sensors candetect application of pressure and the sensor signals can be used by thecomputer controller to modulate and/or arrest bleeding as appropriatethrough alteration of the pressure applied to the blood simulantreservoirs or through modulation of the commands to the control valves.

In one embodiment, blood simulant is created by injecting concentratedliquid colorant and thickener into one-liter bags of saline solution(e.g. Hospira, Inc., p/n NDC 0409-7983-09), which are then agitated tothoroughly mix the components. These bags of blood simulant form thedisposable (yet refillable) simulant containers.

Blood simulant will pass through a series of channels embedded in theheat sinking elements of the central control unit and any othercomponents which generate heat so that it will have a temperature aboveambient when it is released through injury sites. Pressure applied to alimb or artery must be sensed for several of ACS functions, includingthe ability to stop arterial bleeding by either diffuse direct pressure,localized pressure applied to an artery or by application of atourniquet. Limb pressure sensing is also needed to detect palpation bya medic for triggering pain vocalization-for example, in the case ofpalpation of a thigh with presence of a fractured femur.

Pressure Sensing System

A common functional requirement in medical simulators is the detectionof external pressure applied by hand or mechanical device to theexterior of a limb or other body part for the purpose of constricting asubjacent luminal structure such as an artery or vein. An example is thedetection of the pressure applied by a tourniquet to the upper arm toconstrict the brachial artery and stop the flow of blood in the case ofa severe hemorrhage from an artery distal to the point of pressureapplication.

We describe an inventive pressure sensing system that allows themeasurement of pressure applied at any point along a linear path. Thepressure sensing system can be applied to measure the pressure appliedto a variety of linear structures, including tubular structures, andincluding but not limited to simulated arteries, veins and nerves.

The pressure sensing system is durable, flexible, stable, relativelyimmune to noise and can be calibrated.

One embodiment shown in FIG. 10 includes a hollow elastomeric tube(representative materials are polyvinyl chloride (PVC), silicone andneoprene) that is located in a mannequin limb in the position that anartery, vein or nerve would be found in a human. This tube is termed thesense tube. In the case that the pressure sensing system is employed tomeasure the pressure applied to a simulated artery, the tube is termedthe sense artery. This designation distinguishes the tubular sensingelement from the flow artery. A separate component of the hemorrhagesimulation system through which a regulated amount of blood simulantflows.

The sense tube has a diameter that approximates the diameter of thenative target structure (artery, vein or nerve) for which appliedpressure is to be sensed. (In the case of the brachial artery, the mainartery providing blood flow to the arm, the inner diameter isapproximately 3/16″.) The tube is closed at the distal end by means of abarbed plug or other durable closure. The tube may be unbranched(strictly linear) or branched: a tube with a plurality of branches canbe used to emulate the branching course of a native vessel or nerve.

In an exemplary embodiment, the tube is surrounded by a local materialenvironment that emulates the local environment of the native targetstructure. For example, the sense tube may be surrounded by a compliantlayer of material such as a medium-density polyurethane foam thatemulates the viscoelastic material properties of the soft tissuesurrounding a native artery, vein or nerve. Additionally, the tube maybe positioned in proximity to a simulated bone.

The tube is filled with a moderately viscous, incompressible fluid thathas low vapor pressure to prevent evaporation (representative fluidsinclude glycerine or silicone oil). The open, proximal end of the tubeis attached to a solid state gage pressure transducer. This transducercan be located in the trunk of the ACS body, a location that offersmechanical protection and a more controlled temperature environment thanthe limb (factors promoting signal stability and low drift.) Thetransducer voltage signal output is connected to one of theanalog-to-digital converter inputs in the central computing system.

Alternately, the transducer can be mounted within the limb segment, sothat the sense artery does not require separable fluid connectorsbetween the sensing region and the transducer, which could potentiallyadmit air, rendering the pressure measurement inaccurate. In this case,only electrical connections need to be made between limb segments andthe ACS torso.

Pressure applied to the limb via hand or tourniquet is transmitted viathe soft tissue in the limb to the flexible, fluid-filled sense tube,increasing the fluid pressure within the tube. The incompressible fluidtransmits the pressure to the pressure transducer, which converts thepressure signal to an analog electrical signal that is measured by thecentral computer system.

Described below is the application of the pressure sensing system tomeasure pressure applied to a simulated artery to stop the flow of blooddue to a traumatic injury.

The range of the transducer should be sufficient to enable accuratemeasurement of the range of pressure needed to stop arterial flow. Anominal maximum systolic arterial pressure is 250 mm Hg (4.83 psi).Allowing for a factor of two overpressure during application of atourniquet, an appropriate range of pressure sensed by the transducer isapproximately 0 to 10 psi.

The pressure sensing system has the desirable property of localizedmeasurement in a region approximating the spatial extent of an artery.Thus, for example, hand pressure applied to the skin directlysuperjacent to the sensor's tube will elicit a larger signal than if thehand is positioned farther away. The pressure transducer's electricalsignal output is digitized and becomes an input variable in thephysiology system algorithms that control the effector valves thatregulate the flow of blood simulant in the flow artery of the limb. Theprogramming of the central processor compares the transducer outputsignal (after calibration and scaling) to the current value of thesystolic blood pressure, which is taken as a threshold pressure valueabove which arterial flow is cutoff. If the transducer output signalexceeds the threshold value, the central processor sends a signal toclose the solenoid valve that regulates the flow of blood simulant inthe artery in the limb. In this way hand or tourniquet pressure ofsufficient intensity and in the correct placement will result incessation of bleeding.

Because the pressure sensing system measures pressure along a spatialregion conforming to the spatial location of the actual artery, pressureapplied in the wrong location will be less effective or ineffective atgenerating a signal of sufficient intensity to trigger cessation ofblood flow. This provides valuable hands-on experience to a trainee,emphasizing the importance of both magnitude and location of pressureapplication to stop hemorrhage.

In the body, the anatomy of both an artery and the local tissueneighborhood around an artery can influence how pressure applied at theskin surface is transmitted to the artery. For example, if there is anamputation of the lower leg or foot, or severe traumatic laceration tothe arteries of the lower leg or foot, a tourniquet applied below theknee may be ineffective in stopping hemorrhage; a tourniquet properlyapplied above the knee will result in hemostasis. The reason for thedifference is the anatomical position of the arteries above and belowthe knee relative to the muscles and bones. In the upper leg, thefemoral artery, the main artery of the lower limb, is located relativelysuperficially, with only the relatively thin sartorius muscleinterposing between the artery and the skin. The femoral artery feedsinto the popliteal artery in the region behind the knee: the poplitealartery is also relatively easily compressed by application of externalpressure. Below the knee there are three main arteries that supply thelower leg: the anterior tibial artery, the posterior tibial artery andthe fibular (peroneal) artery. For much of its course, the anteriortibial artery runs between the tibia and fibula. A tourniquet appliedbelow the knee will transmit pressure to the rigid tibia and fibula, butthe artery between them will be relatively shielded from receiving thispressure, and hence blood flow through it may not be stopped. This is animportant learning point for trainees. The pressure sensing systemdescribed herein can be implemented to meet this training need. Abranched sense artery (or multiple independent linear sense arteries)can be located so as to emulate the native morphology and course of thefemoral, popliteal, anterior tibial, posterior tibial and fibulararteries. This sense artery (or arteries) can be placed in a similaranatomical relationship to simulated muscles, bones and skin as the realarteries are situated to the native muscles, bones and skin. Atourniquet that is correctly applied to the simulated leg above the kneewill transmit more pressure to the sense artery than a tourniquetapplied below the knee, where the simulated bones (tibia and fibula)shield the sense artery from external pressure just as in the real case.The central programmable processor will measure the pressure and responddifferently in the two cases, actuating appropriate hemostasis in thelower-leg flow artery only when the tourniquet has been correctlyapplied. In the case that separate sense arteries are employed for theupper and the lower leg, the application of a tourniquet (incorrectly)to the lower leg can be specifically detected and this error can berecorded for later review and remediation. In this way, a common errorof training can be detected, trainee performance can be assessed andappropriate feedback can be given to improve future performance.

Additionally, the pressure sensor system can be quantitativelycalibrated by application of the following procedure:

-   -   1. Apply a standard, calibrated blood pressure cuff around the        exterior of the limb containing the embedded pressure sensor.    -   2. Inflate the cuff to a series of pressure values covering the        maximum range of systolic blood pressures to be modeled by the        system. An example series of values would be from 80 mm Hg to        200 mm Hg at intervals of 10 mm Hg.    -   3. At each cuff pressure, measure the signal output of the        pressure transducer.        The resulting series of data pairs (transducer output voltage,        applied pressure) yields a calibration curve that quantitatively        maps transducer signal output to actual applied pressure. Once        the calibration curve is obtained, accurate simulation of        hemostasis is achieved by programming the hemorrhage control        algorithm to stop blood flow only when the sensed transducer        output in a bleeding limb indicates an applied pressure that is        greater than cardiovascular system current value of systolic        arterial pressure (SAP).

Additionally, this pressure sensing system incorporates a means toautomatically calibrate the zero pressure point of the system. Changesin temperature or long-term evaporation of the fluid in the sense tubecan potentially change the baseline (zero) pressure in the fluid. Thesystem therefore incorporates in the programming of the software thatexecutes on the central processor a routine to automatically rezero thepressure sensor at the start of each scenario. The routine executes asfollows: at the start of a training scenario, a startup routine readsthe current value of the pressure transducer output signal for a timeperiod of nominally several seconds, averages the value over this timeperiod, and sets the baseline, or zero-reference, pressure value to beequal to this initial averaged value. All subsequent pressuremeasurements made during the run of the scenario are adjusted by firstsubtracting the baseline value. In this way, the system auto-adjusts forchanges in system parameters that could otherwise create short-term orlong-term drift of the measured pressure.

Pulse Effectors

In one embodiment, palpable pulses are generated in carotid, brachial,radial, femoral, popliteal, and pedal arteries. One embodiment of thepulsation system describes a combination of an electromechanical andhydraulic system. At the location of the pulse point, an elastomericballoon filled with water or alternatively the same fluid as used in thepressure sensing system will lie underneath the surface of the softtissue skin. This balloon will be continuous with a tube that mates witha miniature syringe or similar piston device. The piston device isactuated using either a radio-control style servo, a solenoid, a voicecoil, or other similar electromechanical device. The pulsation units areself contained, and activated electrically. Control signals for pulsesin the extremities are carried through the ruggedized electricalconnectors described in the Skeleton Section.

The R/C servos or voice coil or similar devices will be sufficientlystrong to drive water into the balloons to generate the pulses, but notso strong that if the trainee collapses the balloon by exerting too muchpressure, that they will feel the pulse continue.

Venous System

In one embodiment, a novel implementation of a simulated venous systemreplicates many of the features of the human venous system with respectto the specific procedure of intravenous (IV) fluid administration.Intravenous fluid (saline, Hextend or other crystalloid, whole bloodsimulant) can be administered via I.V. catheter under gravity orpressure feed into most of the common anatomical sites including, butnot limited to, the forearm, jugular veins, antecubital fossa, dorsum ofthe hand, and the sternum. The amount of fluid administered is sensed bya liquid flow sensor that communicates with the central processor. Thephysiological modeling program executing on the central processor altersrelevant vital signs, physiological states and other variables inresponse to the administered fluid.

In one embodiment, the physiologic response to a specific type of IVfluid can be preconfigured by the instructor on the control panel. Thisallows fluid-specific response without the necessity of line-of-siteoperation of the simulator. Oftentimes, a medic will carry only one typeof IV fluid and this feature allows the physiologic system to respondappropriately to the subtle differences in fluid type withoutnecessitating complex and expensive fluid detection systems onboard.

The simulated venous system includes simulated veins. Veins areimplemented using elastomeric tubes that approximate the diameter ofnative veins. The tubing material must be flexible, durable,self-sealing to puncture and with a durometer and other mechanicalproperties that respond with realistic resistance and “pop” tovenipuncture. (“Pop” is a term used in clinical parlance to describe thefeeling of “give” or reduced resistance to pressure experienced at thehand of a practitioner as a needle penetrates the wall of the vein andenters the interior.) Candidate materials for the tubing include latex,neoprene and silicones.

In one embodiment of the system, the simulated antecubital veins(commonly used for IV access in the anterior region of the elbow) aresoft silicone tubing, blue in color, ¼″ outer diameter, 1/16″ wallthickness. In another embodiment of the system, the simulatedantecubital veins are latex tubing, natural (tan) color, ¼″ outerdiameter and 3/32″ wall thickness.

The simulated veins must be initially charged with blood simulant. Theinitial charge of blood must be maintained under sufficient pressure toprovide “flash back” when a needle is inserted into the vein. Thisrefers to the visible flow of blood into an IV needle or cannula whenthe needle is successfully inserted into the lumen of the vein.

The venous system must be able to accept administered IV fluid and storesuch fluid until the end of the training scenario in a collectionchamber entirely contained within the ACS. The amount of IV fluidadministered must be sensed and monitored by the central computerprocessor.

External fluid should flow into the venous system only when the externalfluid head (i.e., the signed height of the external fluid relative tothe height of the venous entry point) is greater than zero.

Fluid should flow back out of a vein if the external fluid head dropsbelow zero: i.e., if the bag of IV fluid drops below the level of thebody (this is an error on the part of a practitioner).

An exemplary implementation is illustrated in FIG. 6. The systemincludes a central blood reservoir (shared with ACS hemorrhage controlsystem), a solenoid valve, an elastomeric bladder, one or more syntheticveins (replaceable, and connected to the system via fluid connectors andfittings), two low-pressure check valves connected in parallel and withopposite flow orientations, a fluid flow sensor and a collecting bag orchamber. In the illustrated embodiment. with the exception of theparallel check valves, all components are connected in series, andconnections are made with appropriately sized polymer tubing and fluidcolmectors and fittings.

In one embodiment, the operation of the system is as follows: During theinitialization start-up procedure for the ACS system, a signal from thecentral computer opens the solenoid-actuated valve to allow bloodsimulant to flow sequentially from the blood reservoir (which ismaintained at a relatively high “arterial” pressure) into theelastomeric bladder, synthetic vein, through the upper check valve,through the flow sensor and into the IV fluid collection bag/chamber.This charges the venous system with blood simulant. Detection of fluidflow by the flow sensor indicates that the system is filled with bloodsimulant, and the central processor then closes the electric pinch valveto prevent further flow.

In another embodiment, the elastomer bladder is a small, expandableballoon of approximately 10 cc volume. It fills with blood simulant andmaintains a low pressure on this volume (via elastic recoil of thebladder walls). This provides a small, low-pressure reservoir of bloodsimulant that is adequate to provide “flash back” into a cannula, needleor saline lock when the vein is successfully penetrated. The upper ofthe two check valves shown in FIG. 5 has its open flow orientationdirected away from the vein; this valve provides a small amount of backpressure in the vein and maintains the distension of the elastomericbladder.

Once IV access has been achieved, external fluid flows into thesynthetic vein, through the upper check valve, through the flow sensorand into the IV fluid collection chamber. The quantity of fluidadministered can be measured by integrating the flow sensor signal toobtain the net volume of fluid passing through the sensor.

In another embodiment, the lower check valve is oriented with thedirection of open flow toward the vein. This allows fluid from thecollection chamber to flow back into the vein and out into the catheterand external IV apparatus should the external bag be dropped below theheight of the body.

In another embodiment, the cracking pressure of the check valves isspecified to be 0.25 psi. This was selected so that an IV bag placed onthe chest of the mannequin, at a height of approximately 20 cm above theinsertion point for an antecubital IV, would have just sufficient fluidhead to allow forward flow into the system. (The pressure head for wateris 1.4 psi/m, yielding a pressure drop of 0.2 m*1.4 psi/m=0.28 psi forthe bag placement described. This pressure is just sufficient to open a0.25 psi check valve.) In practice, this accurately represents theminimum height of IV bag placement where forward fluid flow would beexpected to occur in a real patient.

In another embodiment, the flow sensor is specified to have a flowmeasurement range of approximately 10 to 100 cc/min. This was chosen tomatch the anticipated flow rate of “wide open” IV administration ofapproximately 50 cc per minute. An example fluid flow sensor that meetsthese specifications is the McMillan model G104-03, with a measurementrange of 13 to 100 cc/min at 0.5 % accuracy. Accuracy and minimum flowresolution are important parameters contributing to the accuracy of thevolume measurement derived from integrating (or summating) the flow ratewith respect to time.

In another embodiment, the collection chamber will consist of a rigidchamber enclosing a flexible bag which holds the IV fluid collected. Thebag will have openings at the entrance to receive the fluid, and beattached to a drain valve that passes through the chamber wall. Anormally open valve is attached to tubing that passes through thechamber wall, and enables equalization of air pressure between theatmosphere and the interior of the chamber. Another valve, normallyclosed, connects the chamber to the air pressure source that drives theblood simulant reservoirs.

To empty the collection bag, the equalization valve closes, thepressurized air valve opens and the drain valve opens. The compressedair collapses the bag containing the IV fluid and drives it through thedrain valve. This draining of IV fluid would usually be done duringset-up of the system or after training is completed.

Respiratory System

In a typical trauma response situation the first system that a firstresponder, either medic or paramedic, interacts with is the humanairway. In one embodiment, the airway is anatomically accurate,extending from the mouth and nose terminating at the primary bronchi ina connection system for attachment to the lung portals. Importantlandmarks visualized during intubation are modeled, including, but notlimited to the tongue, epiglottis and vocal cords. Anatomical features amedic is looking for during both standard and complicated airwaymanagement procedures are also represented. This complete head and neckallows oral and nasal intubation as well as surgical airway procedures.The parts of this trainer that are destroyed during the surgical airwayprocedure are easily replaceable, including trachea, mainstem bronchiand outer skin covering with either Velcro closures or a similaradhesive backed material.

In another embodiment, the airway management subsystem is designed tomonitor what is important to the patient independent of treatmentmethodology. For instance, when a trainee is faced with a multiplecasualty scenario, which ACS allows, the trainee may use a combitube onone patient and oral airway on a second casualty, but not have eitherairways or combitubes available for the next casualty in the scenario.The design allows this medic to (appropriately) treat the last casualtyby potentially life-saving mouth-to-mouth resuscitation, and will recordthat as a correct decision. To achieve such a goal, ACS′ monitoring ofairway effectiveness/functionality is driven by the end resultmeasurement of bi-directional airflow and corresponding lung volume, notby monitored user intervention, 3D location of therapeutic devices, orpreprogrammed sequences of events. To achieve design goals of bothstandalone operation and intervention independence, instruments used inintubation do not have their 3D position tracked or their use noted byan instructor; rather the airflow to the lungs is monitored forincreased or decreased flow. Flow sensors located at strategic areas inthe bronchial tree passively measure this flow and feed this data intothe central processor for processing and response generation. Thecriterion for successful intubation then becomes an increase in airflowto the lungs if provided at a time of need. Monitoring this at the lunglevel allows user intervention to be noted at any time during thetraining scenario rather than having an instructor watch what the useris doing at the current moment. Incorrect intubation past the carina andinto a bronchus will be detected by the resulting left-right asymmetryof bronchial airflow.

In one embodiment, the lungs will be created from an elastomericmaterial similar to silicone that can be repetitively inflated anddeflated via compressed air or a bellows system. When at atmosphericpressure, the lungs will resemble a collapsed lung. When inflated withcompressed air from the air pump system, the lungs will expand andstretch the material to fully fill the pleural space. When the air isreleased, the natural material properties of the lung will cause them tocontract, thus forcing the contained air out through the bronchi, pastthe air flow sensors, and then out through the mouth and nose.

In another embodiment, during normal respiration, air will be inhaledand exhaled through the mannequin's mouth and nostrils: exhaled air willbe able to be heard and felt by the medic during primary survey. Thechest will rise and fall if airway is patent and ACS is breathing. Muchlike a human, the lung drivers of the pulmonary subsystem will drawtheir air source in from the nasal and oral openings of the mannequin'shead. If these openings are blocked or constricted, the lung driverswill not be able to draw in as much air. This decrease in lung volumeand subsequent airflow will be detected and recorded by the pair ofairflow monitors located at the termination of the left and rightbronchi. If decreased ventilation persists, the CNS will appropriatelybegin to degrade the health of the mannequin, computing appropriatecardiovascular and neurologic responses, changing vital signs and bymaking the skin appear cyanotic, creating gasping sounds, or creating abucking movement of the torso.

In another embodiment, a section of the ribs on the side of the torsowill be designed to allow easy insertion and removal of the pleuralportal. This portal will also flex and move with the outer rib sectionsthroughout the breathing cycle. The portal will include an outer layerof realistic skin, anatomically correct muscle and fat layers,integrated blood pack for superficial bleeding, and structural rib andconnection system. On the inside of the portal, an airtight pleural sacwill be molded from 10 mil polyethylene to simulate the lining of thepleural space. The lining will be firmly molded to the back of the ribportal to provide an accurate “pop” when a clamp punctures the pleuralspace. The pleural space will be both liquid and airtight. Nested insideof the pleural space will be the elastomeric lung and fittings forconnection to the lung inflation system, the air control system, and theblood flow system. This will be the only connection necessary to installthe entire portal assembly. If a chest tube or chest dart is placed,this entire assembly will be replaced. This design was chosen to reducethe number of expensive sensors and materials that are destroyed duringthe process of relieving a tension pneumothorax or a hemothorax vianeedle decompression or chest tube thoracostomy, respectively.

In another embodiment, the section of skin and tissue layers that aredestroyed during intervention comprise a replaceable portal area. Asection of the rib cage is halved along the ribs and allow for the outersection to open along a hinge. Once opened, a layer of eitherpolyethylene or similar material could be trapped between the twosections forming a simulated pleural membrane which is resistant topuncture, provides adequate “pop”, and creates an air and water-tightspace behind it.

In another embodiment, the polyethylene sheeting is dispensed from areplaceable roll situated along either the sternum or thoracic spine.This would allow easy turn-around of the simulator to allow the nextuser to place a chest tube or chest dart into a pressurized chestcavity. This roll could dispense the sheeting either manually, or beactuated by a motor-driven mechanism.

In another embodiment, when the system is operating, the ACS centralprocessor has the ability to fill the pleural space with either air orblood, depending on the mannequin configuration selected via the controlpanel on the back. As the elastomeric lung is inflating and deflating,air or blood can be leaked into the pleural space, eventually preventingthe lung from inflating. The solenoid valve on the lungs allows actualairflow into the lung with each squeeze of the artificial ventilationdevice while preventing air from leaving, pressurizing the chest cavityand requiring needle decompression. If not treated, the heart andcirculation subsystems will respond to this decrease in airflowaccordingly, as will the tracheal deviation inflation units. During atension pneumothorax, for instance, increased intrathoracic pressurewith decreased venous return can generate distension of the jugularveins: pressurizing the mannequin's jugular veins can simulate this signand alert the medic to presence of this condition.

In another embodiment, the centralized location of the airflow sensorswill naturally detect a decrease in lung volume and translate it intothe appropriate responses necessary for a medic to diagnose and treatthe condition. With proper execution, realistic release of air throughthe chest dart will occur if the pleural space is punctured. This designwill also allow the medic to make a mistake and puncture the lung withthe tip of the chest dart. If this occurs, the lung will no longer beair tight, and will not inflate when the air pump drives air into it.The end result will be reduced airflow past the central sensor, thusallowing the central processor to sense this mistake, and degrade thecondition of the simulator appropriately.

In another embodiment, another feature of this design is that in theevent of a hemothorax, the primary indicators of success are created forthe medic allowing him to determine that his treatment was successful.If the pleural space is filled with blood, as the central processorregisters the amount of blood pumped into the pleural space and adjuststhe baseline condition of the mannequin, the presence of blood alsorestricts the lung from expanding. This is sensed as decreased airflowin the bronchial airflow sensor on that side. This sensing system, incombination with the preconfigured settings on the rear control panel,enables an accurate sequence of physiologic eyents to take place. Thus,when the medic decides to place a chest tube, blood will actually comeout of the chest tube (this being the primary indicator that the tubehas been placed successfully) and if suction is then applied to the tubethe lung will reexpand and airflow in the corresponding bronchus willresume.

In another embodiment, the respiratory system will mimic the structuresof the human system. On each side of the chest will be a rigid, partialrib-cage shaped body. This body will include rib shaped and orientedsculpted features that will be palpable through over-lying soft tissues(which simulate skin, fat and muscle as appropriate). This body will bemounted to such a linkage that it will rise and fall in a manner similarto the human rib-cage motion during breathing. At a minimum, thislinkage will be a four-bar linkage designed such that the lower marginof the rib-cage body moves at approximately a 45 degree angle to thelengthwise axis of the mannequin, and the upper margin of the ribcagebody moves nearly parallel to this axis. More complex motions are alsopossible because the ribcage body has two independent degrees offreedom, enabling both breathing styles that involve mostly the chestand diaphragmal breathing (in which either the upper part of the chestor the lower part rises and falls predominantly).

In one embodiment, the ribcage body forms the outer boundary of a sealedchamber, of the same nature as the pleural cavity in the human body. Theinner surface is part of the mannequin's internal frame, and a flexiblemargin connects the inner and outer rigid elements, thereby creating aclosed cavity. This cavity includes ports mounted in the mannequin'sinternal frame that permits the injection of blood simulant or air, andthe removal of either, so simulate the conditions of hemothorax,pneumothorax and/or tension pneumothorax.

In another embodiment, a closed flexible bag, containing a very soft,foam-like material with large pore spaces occupies the space between theribcage body and the mannequin frame, and act as the human lung. It hasan opening that passes through the internal frame and connects with theairway components described below. The flexible bag is fashioned of atough material that is resistant to punctures from surgical instruments.This bag has the shape of the cavity between the internal frame and theribcage body when the ribcage body is in the “fully exhaled” state. Thesystem is assembled in this condition so that there will be minimalvolume inside the space but outside the bag. Thus, when the ribcage bodyis actuated to “inhale”, the change in volume in the bag is equal tothat of the change in volume of the pleural cavity. This also enablesthe collapse of the bag when blood simulant or air is injected into thepleural cavity to simulate collapsed lung conditions.

In another embodiment, the ribcage body will also have included avariety of openings that will be sealed by overlying soft tissuematerials and/or removable portals. These openings will support thetreatment of the collapsed lung conditions by either releasing airthrough a thoracostomy needle or air or blood simulant through a chesttube. Because the design of the system parallels that of the humananatomy, accurate responses will be presented, namely the sudden releaseof air through the needle or the passage of blood simulant through thechest tube.

In one embodiment, the quantity of air entering and leaving the lungchambers (left and right) will be measured using airflow sensors mountedto the internal frame and forming part of the passage of air from thetrachea and primary bronchii elements to the flexible lung bags. Thetrachea and primary bronchi are fashioned from anatomically realisticmaterials and include anatomy from the oral cavity down to a shortdistance past the carina. The left main bronchus will depart at asharper angle than the right, as is found anatomically.

Rate, depth and rhythm of respiration will be computed and controlled bythe central physiology processor. Respiratory rate and rhythm willrespond to sensed changes in total blood volume, hemodilution and airwaypatency (as sensed by the bronchial airflow sensors). Severe angulationof a fractured C-spine will be sensed and result in phrenic nerveparalysis and respiratory arrest.

Neurological System Model

In one embodiment, ACS can exhibit several levels of consciousness(LOCs): conscious, obtunded, unconscious or unconscious andneurologically compromised (irreversible loss of higher brain function.)ACS′ level of consciousness responds to computed changes in systemicblood pressure and sensed changes in hemodilution and bronchial airflow.If conscious, ACS exhibits signs and behaviors characteristic of aconscious human patient (and the absence of these signs if unconscious):

-   -   The eyelids open and blink at intervals.    -   The eyes move.    -   The eyes and head turn in the direction of a voice or loud        sound.        In one embodiment, ACS possesses the ability to speak. ACS can        also greet a medic by name, based on sensing the medic's        information via RFID tag. ACS could optionally be able to speak        in a language other than English to provide realistic exposure        of the trainee to scenarios involving the treatment of enemy        combatants or local civilian casualties. The head turns in the        direction of touch, grasp or pain to a limb. ACS vocalizes        screams, moans and other expressions of pain in response to        trauma.

In another embodiment, ACS exhibits “muscle tone” when conscious:skeletal joints exhibit a degree of resistance similar to that of anawake and responsive adult. When ACS becomes unconscious, the jointsbecome loose and the body “floppy”. ACS vocalizes slurred or incoherentspeech if obtunded.

In another embodiment, head motion is continuously sensed by solid-stateaccelerometers. If the head is subjected to a sufficiently large forcedue to improper extrication, transport or other handling, theneurological system model will enter a state of concussion and loss ofconsciousness will occur.

In another embodiment, ACS can simulate signs of a generalized(tonic-clonic) seizure, manifested by loss of consciousness, bodystiffening, jaw clenching and simulated rhytlumic muscle contractionsresulting in shaking of the body. The implementation of these effects isvia a seizure state in the neurological system.

In another embodiment, an array of temperature sensors distributed inthe limbs, head and thorax of the system provide environmentaltemperature data that will be used, in conjunction with a coretemperature and thermoregulatory model, to compute entry intohypothermic or hyperthermic states. In either state, appropriate changeswill be generated in vital signs such as heart rate, respiratory rate,and level of consciousness. For example, a hypothermic ACS will becomeobtunded and unresponsive. Computational models of physiology will bedesigned around and optimized for trauma physiology and response totreatment in the field.

The animatronic systems of the ACS enable physical signs of thetransition between consciousness and unconsciousness. Similarly to thehead and neck elements, the joints at the shoulders and hips are alsodesigned to enable a transition between a stiff, posable state and alimp state.

The hip and shoulder joints is to enable a range of motion similar tothose of a normal trauma patient, and in the case of a human-form ACS,this requires a spherical joint at each hip and shoulder location, or acombination of other joints (e.g. serial rotary joints or differentialjoints).

Virtual Fragility

A medical simulator design innovation employed in multiple instances inthe ACS is the use of sensors to actively measure physical variablesassociated with motion, angulation, force or acceleration, followed byprocessing to detect whether the measured physical variable has exceededlimits that would cause injury in an actual nominal human being. We termthis use of intelligent sensing to detect simulated injury virtualfragility. The term indicates that we are replacing the actual fragilityof a mechanical or structural element with a robust embodiment of thesame element combined with sensing to detect the exceeding of limits onphysical parameters that would have caused injury in an actual humanpatient.

For example, a conventional method to detect whether a trainee hasexerted forces or torques on a simulated patient's head of sufficientmagnitude to cause injury to the cervical spine would be to build asimulated cervical spine of such material and construction that thesimulated spine would have similar fracture limits as an actual humancervical spine. The spine would then fracture or dislocate underapplication of input forces and torques similar to those that wouldinjure an actual patient. The disadvantages to this method include thatthe broken elements of the simulated spine need to be physicallyreplaced after each incidence of injury, and there is no automated,quantitative detection and recording of the time, magnitude, or durationof the action causing the injury.

In the inventive virtual fragility methodology, physical fragility isreplaced with intelligent sensing of physical parameters in a robustmechanical structure. In the example of detecting cervical spine injuryjust cited, in one embodiment an angulation sensor (goniometer) andaccelerometers are employed to continuously sense (1) the angle of theskull relative to the chest and (2) the acceleration of the head-bothabsolute acceleration and acceleration of the head relative to the body.These sensors communicate with the central processor which is programmedto detect whether nominal physiological limits of cervical spineangulation and head acceleration have been exceeded. If so, the programexecuting on the central processor records the time and sensor dataduring the injuring event, and further may cause changes inphysiological state—for example, a force to the head of sufficientmagnitude may cause the ACS to enter an unconscious state.

Eye Design

In another embodiment, the ACS eye system provides actuation in a numberof different degrees of freedom. As with human eyes, the eyes pitch(move up/down) in unison, but unlike human range of coordinated eyemotion, they yaw (move left/right) in unison without including vergence(aiming at a single point closer or farther away), and they blink inunison, rather than including a single eyelid winking action. Further,it is possible for the user to manually open the eyelids individually toevaluate pupilary condition.

These capabilities enable the ACS unit to blink realistically, exhibitrolling back of the eyes and closing of the eyelids duringunconsciousness, and look in the direction of human voices or loudnoises, demonstrating responsiveness.

The eye assembly unit includes a base-frame, forming the back of theunit and support arms that extend forward from it. To the support armsis mounted a pitch-frame which pivots about an axis defined by thecenter points of each of the eyeballs. To the right end of thepitch-frame is mounted an R/C servo, with its rotational axis passingtlrough the center point of the right eye, and perpendicular to theplane of the pitch-frame. The right eyeball unit is mounted to the R/Cservo output shaft and to a bearing concentric with it below the R/Cservo to provide stability. A control arm extends backwards from theservo output shaft behind the eyeball. The left end of the pitch-frameincludes bearings to mount the left eyeball unit. The left eyeball unitincludes a control arm extending backwards from its axis of the samelength as the right eye control arm. The control arms are connected toeach other by a rigid link such that when the right eye R/C servo turnsthe right eye, the left eye turns through the same angle due to theaction of the connecting linkage (control arm, rigid link, control arm).This accomplishes the coupled yaw motion of the eyes. Depending on thechoice of length of the rigid link, the eyes may gaze in a perfectlyparallel direction, or if slightly longer, may give the eyes a slightinward fixed vergence. The latter might give the user a slight sensethat ACS is focusing on them, rather than to the distance.

The pitch-frame has mounted to it an R/C servo that may have itsrotational axis passing through the rotary axis of the pitch-frame, orit may be parallel but offset to it. In the former case, this servodirectly drives the pitch action of the pitch-frame. In the latter, aseries of gears or a toothed belt drive will transmit the torque fromthe servo to the motion of the pitch-frame. This accomplishes the pitchmotion of the eyes, moving in unison.

An alternative design mounts the servo to the base-frame, and through agearing mechanism, with a gear section mounted to the pitch-frame,drives the pitch-frame about its axis. The eyes are protected fromcontamination and damage by a sealed clear housing (as shown in FIG. 8).Unlike this figure, the eyelids are mounted outside of the housing toprovide manual access to them. The eyelids are mounted about the sameaxis as the pitch-frame. A single servo, mounted to the base-frame, withits axis parallel to the eyelid axis controls the eyelid action.

One embodiment includes manual actuation of the eyelids with controlarms extending up and down from the eyelid component at the location ofthe rotary bearings. The upper and lower ends of the arms are attachedto elastic cables that extend backwards from the eyelids. They areconnected to control arms extending up and down from a shaft concentricwith and mounted to the eyelid servo. As the servo rotates the uppercontrol arm backwards, the eyelid opens, and vice versa. The presence ofthe elastic cables permits a user to manually hold the eyes closed whenotherwise in an open state, or open when in a closed state. Uponrelease, the eyelids return to the state determined by the ACSconsciousness level. The elastic cables prevent damage to the servo dueto excessively rapid back-driving, which could occur if there was ageared or belted connection between the servo and the eyelid components.Speed of eyelid motion is controlled by the rate of servo motion, andincreased further by selecting long servo control arms and short eyelidcontrol arms.

Another embodiment describes the range of motion of the eyelids limitedby hard stops in the skull/face unit. The eyelid servo is commanded toopen the eyes slightly beyond the open limit, and close beyond theclosed limit. In this manner, there will be a slight preload (due to theelastic cables) that prevents the eyelids from being free to oscillate(which remains a possibility if the eyelids are commanded to anintermediate position between open and closed). Suitable selection ofbearing materials with some finite friction minimize this, though caremust be taken so that the friction is not so high that the elastic cableforces are lower than the friction forces.

In one embodiment, the eye assembly is a self-contained unit that couldbe easily replaced if damaged, rather than requiring disassembly ofexcessively large numbers of components from the ACS head. The eyes andconstructed within a sealed, self-contained unit. The housing preventsdamage to the system and prevents fluids from entering the actuatorsystems. The eyes are actuated so that they pitch and yaw in unison, andthe pupils are independently controllable. Another embodiment employsservomotors of the type used in radio-control vehicles to actuate theeye motion. The eyelids are mounted externally to the sealed unit sothey may be manually opened by users. A cam mechanism opens both eyelidssimultaneously, which close upon retraction of the cam through a springwhich maintains contact between the eyelids and the cam. This spring isof sufficient compliance so that the user may open the eyelid witheffort similar to that required to open a human eyelid.

An alternative embodiment employs low pressure pneumatic cylinders todrive the eyelid motion. The pressure is selected such that it is nothigh enough to prevent manual actuation, but is sufficient to maintainthe open or closed state regardless of the posture or orientation of thehead.

The irises are constructed as toroidal balloons, mounted such that theyare prevented from expanding radially when inflated, thereforecontracting the pupil instead. They are actuated pneumatically.

Skeletal Chassis

In one embodiment, the skeleton is the fundamental structural element ofthe entire system. In an exemplary embodiment, the ACS skeletal chassisis extremely durable, made from a combination of non-brittle resin andreinforced metal components, and naturally articulated to move andbreathe like a real human. For example, the rib sections are articulatedonly in the areas necessary to ensure that a medic can determine thatthe casualty is breathing, both unilaterally and bilaterally, and canrealistically administer CPR.

The skeletal system is anatomically correct in areas that are importantfor correct diagnosis and treatment, as well as in areas that affectnatural movement. The skeleton articulates in the appropriate majorjoints: cervical spine, lumbar spine, shoulders, elbows, wrists, hips,knees, and ankles. Anatomic position of the skeleton is monitored withflex sensors in key locations, while overall body location in thetraining environment is recorded by an on-board GPS unit, allowingtracking of the system's position during initial treatment andevacuation. Reference landmarks are obvious and durable: for example,the inguinal ligament is a durable landmark to identify the femoralpulses.

The skeleton has tliree “modes”: conscious, obtunded, and unconscious.Conscious mode keeps certain “muscle groups” tensed to aid in movementand transportation of the mannequin. However, if the on-board centralphysiology processor determines, on the basis of continuous observationof physiological parameters responding to injury treatment, that thecasualty loses consciousness, the “muscle groups” release and theskeleton goes limp, and becomes very difficult to carry. This can bedone either with mechanical solenoid movement or with electromagnets atkey areas such as the hips and scapulae. Other embodiments would bereleasable detent-type mechanisms points smoothly “snap” into variouspositions, but the detent mechanism is retractable to allow freemotion); air bladders pressing friction pads against each other withinthe joint; and, for the spine, running a tension cable through itslength, which can then be tightened or loosened to change neck tone.

The cervical spine incorporates an accelerometer to provide relativeposition for the head unit. The skull has an accelerometer to registerforces sustained during treatment and movement of the casualty. Thisdata indicates when serious additional injuries are sustained during thetreatment phase after initial injury.

In one embodiment, in the same way that the intercostal muscle groupscontract and the costo-vertebral and costo-chondral joints flex tocreate the rise and fall of the chest, ACS creates similar flexibilityusing contractile actuators to drive the rib cage up and down. This isin keeping with the paradigm of duplicating, where feasible, the naturalanatomy of the body and its functions.

In another embodiment, the shoulder system combines several teclmologiesinto a novel system for replicating accurate anatomical movement ofhuman shoulder anatomy. Beginning at the sternum, the clavicular strutis created from an accurately shaped 0.50″ to 0.75″ metal rod. Thesternal termination of this clavicular strut is comprised of ahigh-displacement ball end which is held in place by a 0.25″ ODpartially-threaded bolt. The opposite end of the clavicle connectsrigidly to a scapular hub via either a threaded connection with asetscrew, or with a pressure fitting which when clamped prevents theclavicle from rotating relative to the hub. For extreme torsionalpressures, the clavicular strut may be through-bolted to ensure properalignment and prevent rotation within the hub if substantial pressure isapplied to the shoulder assembly. The location of the joint between theclavicular strut and the scapular hub mimics that of the acromion inreal human anatomy. It's height and width should replicate theappropriate landmarks to provide realistic feeling to the user.

Rigidly attached to the back of the scapular hub is the second half ofthe clavicular wishbone. This wishbone is attached to a central rotarydamper that provides a configurable amount of damping force against therotational forces exerted by the wishbone assembly.

The design of the jointing systems allows central processor control ofmuscle tone, but every joint has a built in amount of tolerance to allowa natural amount of play when articulated. This tolerance enables ACS tofeel like a real human when moved, carried, or lifted. These tolerancesare specific to each joint location.

The neck employs a combination of pneumatic cylinders, flexible cablesand a heavy spring to generate motion and changes in muscle tone. Onecylinder changes the compression of the spring, which is constrained byan upper plate, and compressed by the cylinder below. The cylinder isrigidly mounted to the thoracic skeletal structure. The upper plateis,constrained by three or more cables. When in the uncompressed state,the neck is limp, and can easily be moved manually. It is further ofinsufficient stiffness to support the weight of the head againstgravity. When compressed, the spring shortens and increases tension inthe cables. In this state, the neck is of sufficient stiffness tosupport its own weight and resists manual manipulation.

The head is caused to turn in the yaw direction through the use of arotary pneumatic actuator. It has a range of motion of approximately 60degrees in each of the left and right directions. The flexibility of theneck allows slightly more motion in either direction.

Alternative embodiments include the replacement of the pneumaticcylinders with electromechanical linear actuators such as lead screwsthat cannot be back-driven. The shoulder joint employs a ball jointsimilar to those used in camera tripod mounts. It allows sphericalmotion, and is controllable such that resistance to motion can bevaried. When in high-resistance mode, the arms will resist motionrelative to the body, making it easier to move the body as a unit. Whenin low-resistance mode, the arms will be limp.

Skeletal motion is detected via a pair of perpendicularly orientedaccelerometers. These were selected due to their minimal drift, hightemperature tolerance, minimal size, and cost-effectiveness. Thehorizontal sensor is oriented along the axial plane of the skull andrecords forward and backward motion as well as side-to-side movement ofthe skull relative to the base of the neck. A second accelerometer isangled at 90 degrees to the first sensor and provides twisting data ofthe skull relative to the base of the neck. These sensors are housed ina shockproof and waterproof container that keeps them out of harms way.

At the base of the neck is a second pair of similarly orientatedaccelerometers that provide a reference plane for the ACS body. Withoutthis, it may not be possible to differentiate that the head of ACS istwisted to one side from the whole body of ACS being in a similarposition. These systems function regardless of orientation and do notrequire a calibration phase due to their method of detection. Thesensors selected use a small heating element to create micro-eddies ofthermal difference to gather position data relative to gravity.

When the head accelerometers detect a difference in the angle of thetorso, they will attempt to orient the head so as to keep a parallelhorizontal plane relative to gravity. This assumes that the skeleton isin conscious mode. The purpose of this is to make the head movement morerealistic. It would do this by articulating the neck actuatorsaccordingly. Body angle (orientation) will be continuously recorded-if amedic fails to roll a body to examine the back for an exit wound, forexample, this can be seen in the data record.

Environmental Design

The central processing unit is mounted within a reopenable andresealable container mounted within the structure of the internalskeleton. Connections leaving the container are sealed through theapplication of high temperature silicone. Circuitry and otherwiseexposed connectors are similarly sealed throughout the system. The audioinput and output system in the head (i.e. loudspeaker and ear-mountedmicrophones) can be provided as commercial waterproof systems.

Wiring and tubing that passes through joint regions is selected androuted so that they have an unlimited lifetime of repetitive flexing orbending. Wiring in rigid regions passes through protective channelswithin the skeleton's members. Rugged electrical and fluid connectorsare used at the limb attachment points (upper and lower legs and arms),and the connectors are physically reinforced using aligned rods andsockets, and attachment is achieved using robust mechanical latches. Oneembodiment uses a latching system similar to that of airline seat beltbuckles.

One possible jointing system involves the use of light pipes as a mainbridge for cross-joint communication. A system of infrared LED emittersand receivers would allow non-contact transmission of data across majorarticulated areas such as the elbow and knee. Semi-circular disks ofacrylic or similar plastic would reflect light passed through the broadside of the plastic, through its length, out to the edge where similarlyit would be received by the opposite LED. This configuration would alsoallow the joint condition to degrade gracefully over time as no matterhow scratched the joint lighting system becomes, the receiver would besensitive enough to compensate. The use of infrared light would permitusage at night without light leakage.

Another embodiment for the power transmission is to incorporate positiveand negative sides to each long bone member. The outer half of the bonecould be a substantial grounded electrical member as well as providingthe strong structural qualities found in conductive metals. The centerhalf of the bone would provide positive power to the extremities. Brushconnectors or some large, easily cleanable contacts would facilitatepower transmission reliably during harsh conditions found in militarytraining environments.

In anexemplary embodiment where ACS is a tetherless, autonomous system,there is the requirement that it has an internal power supply.Embodiments can include compressed gas and rechargeable batteries. Lesspreferred systems might include fuel cells or hybrid engine/generatorsystems.

Compressed gas can be used to provide motive force for mechanicalactuators and brakes, however to provide a sufficient “lifetime”, highpressure gas is employed with a compressor to recharge the unit betweenuses. In addition, the embedded computer and control valves wouldrequire electrical power.

In one embodiment, ACS makes use of rechargeable batteries to supplypower for the computer, actuator, brake and sensor systems. A small aircompressor, run intermittently, is employed to pressurize the bloodsimulant reservoir. One exemplary system is the Milwaukee V28 batterysystem. This commercially available battery system was designed for usewith heavy-duty cordless power tools, and is currently has the highestpower storage capacity of any cordless power tool battery. The rechargecycle is one hour in duration.

The battery is rated at 3 Amp-hours at 28V. A single battery can supplythe central processor module at its estimated power consumption of 10 Wfor eight hours of continuous use. In one embodiment, two batteries areused to provide power for the total system, with care taken to minimizepower consumption in the braking and actuator system.

An exemplary embodiment provides a user-friendly system to recharge thebattery packs. A recharging system converts power supplied from suchsources as 110 VAC typical of house-hold outlets, or vehicular 12 VDC or24 VDC, or others that may be deemed useful by the user, into DC currentand/or voltage trajectory that rapidly charges partially or fullydischarged battery packs. It consists of the electrical conversion andcontrol circuitry, and a portable housing which includes space toenclose the circuitry and form fitting enclosures into which the batterypacks are inserted to mate with water resistant connectors of a typewhich mate with those integral to the battery packs. The rechargingsystem is splash and rain resistant to support outdoor use or use inenvironments in which incidental contact with water or other fluids ispossible.

ACS Control Panel

In one embodiment, tactile controls are used: robust physical knobs withdetents that click into position, switches that give unambiguous tactilefeedback and clear visual indicators. Physical controls have thebeneficial property of unambiguous affordance: they move and actuate insimple, intuitive ways. Rotating a dial or pushing a switch is intuitiveto every user—whereas training (or at least a user manual) is oftenrequired to understand the interface conventions of complex software,particularly if hidden menus and modal dialogs are used.

In another embodiment, continuous rotary encoders and momentary contactpush-button switches (i.e., stateless controls) with LEDs to indicatethe parameters selected by the controls. Compared to conventional rotaryand linear switches that indicate their position by their physicalposition, stateless controls offer several advantages. First, thisapproach permits one-button reset of the entire control panel. Whensetting up a new scenario, it is often helpful to start with a cleanslate. With conventional controls, all dials and switches must bephysically returned to their “off” or default positions to reset thesystem. This is time consuming, and if a previously set switch isinadvertently overlooked, a function may be mistakenly selected. Byusing stateless controls to select parameters which are indicated byseparate LED displays, we can perform a “soft reset” that returns allparameters to their “off” settings-this is then appropriately indicatedby the LEDs. The controls themselves do not have to be moved to performthis reset.

In another embodiment, the use of stateless controls and separateindicators also enables the capability to set or change any parameter onthe control panel remotely via the Instructor Remote Monitor. The changeis wirelessly communicated to the system, which then sets theappropriate parameters and changes the corresponding LED indicators. Thecontrol panel always shows the correct current settings of allparameters, even if they have been changed remotely.

In another embodiment, the configuration of the panel is obvious at aglance: there is one control for each function. The current setting foreach function can be determined simply by looking at the control. Thereare no “hidden controls” (such as functions hidden in drop-down menus):a medic instructor can learn ACS′ functionality by inspection of thecontrol panel. In a very real sense, the control panel isself-instructive: it is the user manual.

In another embodiment, the controls can be set in any order and changedat any time: there are no sequences to learn or memorize. Each controlspecifies one and only one action and nearly all functions areindependent of other controls (a few dependencies are appropriatelyhandled: for example, if another action is set to occur duringnon-responsive cardiac arrest, the action will not execute). In theterminology of user-interface design, this is a non-modal interface,offering direct access to each of ACS' features.

Numerical values for activation times and durations are entered viarotary encoders and displayed with backlit LCD displays. Activationtimes are specified in minutes from the scenario start time (t=0).Bar-graph indicators will be used to show the battery charge, RF signalstrength from the Instructor Remote Monitor, and the levels of theinternal reservoirs for blood and IV fluid.

In one embodiment, the control panel will be protected by a hingedcover. A flexible gasket encircles the periphery of the cover, sealingthe control panel from moisture and dirt. All controls will beilluminated so the panel can be configured during field exercises atnight. (Panel illumination can be turned off if desired.) A microswitchor magnetic proximity switch keyed to the cover hinge motion is used toautomatically turn off the indicator lights and panel illumination whenthe panel is closed to conserve power (a “refrigerator light”mechanism).

Audio Output System

Audio output such as speech, labored respiratory sounds and othervocalizations is digitally recorded in a studio, then edited, formattedand transferred to non-volatile solid-state memory in the centralprocessor. The individual sounds are stored in an indexed database; soindividual phrases, responses or sounds can be triggered as desired.

When triggered, the stored digital waveforms are sent to adigital-to-analog (D/A) converter and output to an audio amplifier andloudspeaker. In one embodiment, the speaker is a long-throw voice coilmodel with a polypropylene cone and a butyl rubber surround, sourcedfrom a supplier of car stereo systems-built to be weather and shockresistant and designed to function reliably in extremes of temperature.The speaker is mounted in the skull cavity (not the oropharynx, to avoidinterference with airway assistive devices) with acoustic channels builtinto the zygomatic arches and other facial bones so that the sound willbe perceived as emanating from the face.

The human voice is a cue for presence and simulator realism, so toachieve the highest sound fidelity a preemphasis frequency equalizationsystem can be employed. The frequency response of the audio outputsystem is measured (the amplifier and speaker, with the speaker in placein the head.) A 20 Hz to 20 kHz frequency sweep is played through theamplifier and speaker and the resulting sound output is recorded at atypical “medic distance” from the body using an instrumentation-grademicrophone with a flat frequency response. The microphone signal isdigitally recorded and Fourier transformed (using Matlab) to obtain thefrequency response of the audio output system. A compensating frequencyresponse function is then computed: this function gives the frequencyresponse curve that “flattens” the amplifier-speaker frequency responseto produce an even response over the audio range. The digital recordingsof voice and other vocalizations are preemphasized (i.e., prefiltered)with the compensating frequency response curve before being stored insystem memory for playback. The result is high-fidelity sound output forthese recordings, despite the relatively small speaker diameter andother acoustic constraints of a speaker system mounted in the volume ofa human head.

Instructor Remote Monitor

In one embodiment, while no additional apparatus or controller isrequired to set up the desired trauma scenario, an illustrativeembodiment employs a wireless monitor to give an instructor the ability,if desired, to program, start and end a scenario remotely. The monitoralso permits an instructor to view vital signs and other data in realtime, monitor scenario progress, and remotely alter the scenario asdesired. Access to more advanced features and configuration data of theACS computing core can be accessed via the Advanced panel on the tabletPC. ACS will allow real-time display and control of the physiologicsubsystems and their interaction throughout its operation.

Automated Debriefing

Once the training sessions have been completed and the simulation hasended, in one embodiment the Scenario Coordinator will use the wirelesstablet PC to download the recorded medical treatment data via a simpleGraphical User Interface (GUI) on the tablet PC. This data representsall of the variables and data points collected by the sensors throughoutthe mannequin during the training scenario. This data is then parsed bythe Automated Debriefing software and turned into a series of talkingpoints that are correlated to medical events that occurred during thesimulation.

The purpose of the Automated Debriefing system is not to replace themedic instructor, but to generate talking points around which a higherlevel of conversation can take place between the unaided medic and theinstructor. Because ACS functions as a standalone unit, the instructormay not be present to witness the treatment provided to the casualty.During these debriefing sessions, the instructor will have access to theidentities of the medics, the entire medical treatment history, vitalsigns, hemodynamic values and interventional events that were generatedor controlled by the medics during the FTX as well as access to thespecific mannequin configuration settings which were preset by theScenario Coordinator at the beginning of the session. This data willprovide the instructor a better tool for reviewing the decisions themedic made.

Because the physiologic data collected by ACS can be compared to theconfiguration settings established prior to the FTX, and because thesystem design allows intervention independent interpretation oftreatment, standardized debriefing summaries can be generated. Thisstandardization ensures consistent training among instructors, aMilitary Occupation Specialty (MOS) which rotates relatively frequently.Decisions regarding relative weighting of treatments, criteria forsuccessful treatment and triage priorities can be established by theinstructor corps.

In another embodiment, by design, ACS simplifies training requirementsfor the medic instructors. Basic system operation is simple. Access tothe deeper level programming possibilities is possible through thetablet interface, allowing instructors with more advanced training tomodify training requirements or specific areas to be tested.

In another embodiment, by combining continuous physiology andtime-integration, the new medic training system can createindividualized milestone-linked timelines of care. This capabilitytransparently records time of injury, time to airway control, time tohemorrhage control, effectiveness of treatment and other importantmilestones identified by the instructors. At the end of each exercise,every student is be given a personalized time-stamped record ofintervention which will serve as the student's physical record ofperformance and which can be archived electronically as the instructor'srecord of individual and class performance.

Description of Exemplary Embodiments

FIG. 6 is a schematic drawing of combined pneumatic and blood simulantsystems of the ACS. Components include an air and fluid pressurizationblock 600, a neck articulation system 610, a hemo-pneumothorax system620 and limb trauma modules 630, 640, 650, 670, 680, of which aplurality are shown.

The function of the air and fluid pressurization block 600 is to storehigh pressure air and provide air at lower pressures to the neckarticulation system 610, and the fluidic systems of the ACS. Highpressure air is stored in one or more reservoirs 601 at 150 psi, whichis reduced to 30 psi and 4 psi through two different regulators 602,603. The 30 psi air is supplied to the neck articulation system 610,described below. The low pressure air is supplied first to the bloodsimulant pressurization chambers 604 through a normally closed (NC)two-way, three-port solenoid valve with spring return 605. Upon startupof the ACS, this valve opens, pressurizing the blood simulant. Duringrefit of the ACS, the valve 605 returns to its NC state, and thepressurized air is allowed to exhaust through a silencer 606. The lowpressure air is also supplied through a normally open (NC) two-way,three-port solenoid valve with spring return 607 to the intravenous (IV)fluid collection and ejection chambers 608. During normal operation, thechamber 608 is exhausted, allowing the IV fluid collection bag 609 toexpand as it accepts administered IV fluid. During refit of the ACS, thevalve 607 opens, forcing IV fluid out of the collection bags 609 andthrough an NC two-way, two-port valve 690 and out of the ACS.

Installation and replacement of the blood simulant containers 610 isenabled through the use of self-sealing quick-disconnect valves 611.Measurement of hemorrhage of blood simulant is accomplished with a flowsensor 612, and the quantity of IV fluid administered is measured with asecond flow sensor 613. Blood simulant is prevented from flowing outthrough the ACS fluidic systems prematurely by a NC two-way, two-portsolenoid valve with spring return 614.

The ACS torso includes four quick-disconnectstructural/fluidic/electrical (SFE) connectors 691, one each located atthe left and right shoulder and left and right hips joints. Eachconnector 691 includes fluidic channels for blood simulant and IV fluidand electrical connectors to support sensors and actuators describedabove and below. To these connectors 691 may be attached any appropriatelimb trauma module 630, 640, 650, 670, 680, examples of which aredescribed as follows.

The upper limb (either arm or leg) traumatic amputation module 630includes a mating SFE connector 692. As IV fluid will not beadministered to a traumatically amputated limb, there is no active IVfluid connector element in this module. The blood simulant connectorsupplies fluid to three outlets. Two, corresponding with arterial flow631 and soft tissue seepage 632 are controlled with a NC two-way,two-port, spring returned solenoid valve 634, which enables thegeneration of pulsatile flow and the cessation of flow upon propertourniquet or other hemostatic device placement. The third outletcorresponds with bone marrow seepage 633 which is modulated only byinternal blood pressure.

The upper limb, undamaged, IV collection module 640 includes a matingSFE connector 692, and at the distal end, a second SFE connector 693 toattach to a lower limb module 660. The blood simulant enters the module640 and is channeled either to the lower limb module 650, 660 or to theIV fluid collection loop 641, 642, 643, 644 by a two-way, three-port,spring-returned solenoid valve 645. The fluid flow to the lower limb650, 660 is understood from the schematic. The flow to the IV fluidcollection loop 641, 642, 643, 644 is momentarily enabled during refitto fill the loop with blood simulant. The loop includes a self-sealing,elastomeric vein 641 and a pair of one-way check valves 642, 643 withlow, but non-zero cracking pressure, which are arranged anti-parallel toeach other, in series with the IV loop. The check valves 642, 643 causea back pressure which causes blood simulant to slightly expand theelastomeric vein 641 (and optional elastomeric bladder 644 to increaseavailable simulant). This pressurized blood simulant is expelled throughan IV needle placed into the vein 641, recreating the phenomenonreferred to as “flash-back”. The check valve 643 oriented to allow flowback towards the elastomeric vein is present so that if an IV needle isplaced and either an IV bag is placed below the elevation of the ACS, orif the needle is left unattached and the arm is lowered below the IVcollection chambers 608, IV fluid will flow out of the needle. This lossof fluid is measured by the flow sensor 613 mentioned above.

The lower limb traumatic amputation module 650 is hydraulicallyequivalent to the upper limb traumatic amputation module 630. Its SFEconnector 694 is designed to enable connection only to the distal end ofa matching upper limb IV collection module 693, preventing directattachment of a lower limb to the shoulder or the hip.

The lower limb IV collection module 660 is hydraulically equivalent tothe upper limb IV collection module 640, with the exception that thereis no distal SFE connector 693 to attach additional limb segments.

The schematic diagram shows a variety of possible combinations of upperand lower limb trauma and IV collection modules. As illustrated, thisconfiguration includes: a traumatic upper arm amputation module 630; acombination of an upper arm IV collection module 640 and a lower armtraumatic amputation module 650; a combination of upper and lower leg IVcollection modules 640, 660; and an upper leg traumatic amputationmodule 630. It should be recognized that the function of the traumaticamputation modules would be duplicated in a non-amputation module withmajor hemorrhage functionality.

The schematic shows that the ACS torso contains the systems to supplyand measure blood simulant lost, collect and measure IV fluidadministered (and/or lost), control the limb module valving and pulsing(see below) and record module sensor signals (e.g. tourniquet pressuresensing, see below).

The ACS torso also contains the pleural cavities 621, which are capableof simulating hemo-thorax, pneumo-thorax and tension pneumo-thoraxconditions. The conditions are created in the ACS by admitting lowpressure air or blood simulant into one or both of the pleural cavities621. This flow is controlled by a series of NC two-way, two-port,spring-returned solenoid valves 622. During refit, the low pressure airor blood simulant is ejected from the pleural cavities 621 by openingexhaust valves 623 (also NC two-way, two-port spring-return solenoidvalves).

The neck articulation system 615 also part of the ACS torso, and iscomprised of four McKibben-type air muscles 616, each of which isactivated by a NC two-way, three-port, spring-returned solenoid valve617, all of which are exhausted to a common silencer 618.

FIG. 7 shows exemplary skeletal 700 and soft tissue elements 750 of thelimb modules. On the left part of the FIG. 750 can be seen the flowchannels for bone marrow seepage 751 (running through the femur segmentincluded for illustrative purposes) and the soft tissue seepage 752,which passes through the muscular elements of the leg 753 but endswithin the open cell foam 754 at the exposed end of the muscle material.Open cell foam is similarly used in the exposed end of the seeping bone755. Arterial bleeding is achieved through a tube 756 placed such thatits path corresponds with typical anatomy (e.g. femoral artery). Theright side 700 shows a limb trauma module with complete dissection ofthe long bone 701, 702, the channels for fluid and electrical conduits703, which prevent excessive bending during flexion and extension of thejoint 704 (knee or elbow), and a roll joint 705 to enable twisting ofthe lower extremity 706. The knee or elbow joint angled surfaces 707 aredesigned to allow accurate limits of flexion and extension of the limb700.

FIG. 8 shows an example of the SFE connector 800, 850. It includes inthis embodiment, proximal 800 and distal 850 structural elements of thelimb (e.g. humerus just below the shoulder and above the SFE connector,and humerus below the SFE connector), fluid conduits 801, 851terminating at the SFE with self-sealing quick-disconnect fittings whichallow unrestricted flow when the SFE connector is mated and electricalconnectors 803, 853 with sufficient conductors to support all distalsensors and actuators. The SFE connector locks to prevent accidentaldisconnection through the use of the spring and peg system 804 shown inthe figure, but could instead make use of a threaded external sleeve orbayonet-style connector.

FIG. 9 shows a tourniquet pressure sensing system 900 comprising asolid-state pressure sensor 901 connected to a fluid filled elastomerictube 902, which is molded closed at its distal end or closed with a plugor other seal 903. Electrical connections 904 from the pressure sensingsystem 900 include power and ground lines 904 from the ACS sensor powerbus and signal output to the data acquisition system of the computercontroller.

FIGS. 10 and 11 show examples of pulse generation units 1000, 1100placed in the ACS torso where carotid and femoral pulses are normallydetected, in the arm modules at the brachial and radial pulse points andin the leg modules at the popliteal and pedal pulse points. FIG. 10shows an example of a fluid-based system 1000. A fluid-filledelastomeric tube 1001, sufficiently long to extend through the entireanatomical region where a pulse would be detected, is attached to anopen-ended cylinder 1002 (in this case the distal end of a syringe). Theplunger 1003 of the syringe is mounted to the shaft 1004 of a push-typesolenoid 1005. The solenoid 1005 drives the plunger 1003 under thecontrol of the ACS computer controller to pressurize the elastomerictube 1001 in time with the pulse rate determined by the physiologicalmodel. The solenoid 1005 may have a spring return if the recoil of theelastomeric tube 1001 is not sufficient to overcome the friction betweenthe syringe body 1002 and the plunger 1003.

FIG. 11 shows an alternate pulse generation unit 1100 which iselectromechanical. A solenoid 1101 is mounted to a hollow tube 1102, theside of which is removed over a region corresponding with the zone overwhich a pulse would be detected. The solenoid shaft 1103 pushes on theend of a buckled thin beam 1104, which is anchored at the distal end ofthe tube 1102, and bends outwards away from the axis of the tube 1102.The beam 1104 is embedded in a soft, polymeric material 1105 to simulatethe softness of a pulsating artery. In both examples of pulse generatingunits 1000, 1100, the solenoid 1005, 1101 and pulsing elements 1001,1104 are embedded within the soft tissue of the limb module (not shown)and attached to the structural elements of the skeleton 1006, 1106(human bones shown in these figures for scale).

The ACS features unilateral and bilateral chest motion and will respondto appropriate cardiopulmonary resuscitation. In addition, it respires,drawing in and exhaling room air when not in pulmonary arrest or subjectto an obstructed airway. This is accomplished in a biomimetic fashion,in that the motion of the chest wall expands the volume of the pleuralspace, drawing in air through the airway system (see above), andexpelling it when the chest wall contracts.

FIG. 12 shows an embodiment of the chest wall motion system 1200, inwhich the back of the torso 1201 includes rigid, immobile elements, andthe front left, and front right surfaces are separate rigid costalbodies 1202, 1203. In addition to the costal bodies 1202, 1203, thesternum 1204 is represented by an anatomically molded structure which ishinged 1205 at the location of the junction with the first set of ribs.The sternal 1204 structure's lateral edges overlie the inner edges ofthe costal bodies 1202, 1203. The costal bodies are each attached to theinternal frame 1206 of the ACS torso via pin joints 1207 and rigid links1208, 1209, such that each costal bodies 1202, 1203 form the ungroundedlink of a four-bar mechanism. By careful design of the lengths of thelinks 1208, 1209 and the distance of their junctions with the ACS frame1206 and the costal bodies 1202, 1203, the path of motion of the costalbodies 1202, 1203 can be made to emulate the motion of real ribs. Inparticular, the path of the lower margin of the costal bodies 1202, 1203tends to be upwards (towards the head) and outwards away from midline ofthe body, and the upper margin of the costal bodies 1202, 1203 tend tomove more directly upwards. The links 1208, 1209 are curved in shape toconform with the inner surface of the costal bodies 1202, 1203 when inthe fully exhaled state.

The motion of the four-bar mechanism can be accomplished in a variety ofways, including rotary actuators mounted at any of the four pin joints1207, linear actuators acting between a hinged joint on the ACS frame1206 and a point along the length of one of the links 1208, 1209. Apractitioner skilled in the art will conceive of other methods inaddition to these. In this embodiment, each of the four-bar mechanismsis driven by a ball-screw mechanism, driven by an electric motor. Theball-screw provides a low-friction, back-driveable linear actuationmode, such that a sufficiently large force will prevent chest wallmotion (and passage of air into the ACS lungs).

Also shown in FIG. 12, there is a spring element 1210 between thesternal body 1204 and the ACS frame 1206. This spring 1210 has astiffness of approximately 50 lbs/inch, corresponding with the stiffnessof the human chest in response to the application of the chestcompressions of CPR. The range of motion of the spring 1210 is slightlymore than 2 inches, corresponding with the ideal compression depth ofCPR. Sensors to detect depth of compression are mounted concentricallywith the spring 1210, but may also be placed at the pivot point of thesternum 1205, or in other locations.

The treatment of hemothorax and pneumothorax require dissection throughthe chest wall at an appropriate location and puncturing through thepleural layer on the inside of the chest wall to enable placement of atube that will drain air, blood or other fluids. The treatment oftension pneumothorax requires the insertion of a hollow needle throughthe chest wall to relieve the pressurized air within the pleural cavity.

FIG. 13 shows the configurations of separate chambers within the ACStorso, the upper cross section showing the chamber where tensionpneumothorax is simulated, the lower cross section showing the chamberwhere pneumothorax and hemothorax are generated.

The tension pneumothorax chamber 1300 comprises a section of theanterior costal body 1301 in the region corresponding with the firstthrough the fourth rib and interior sealed walls 1302. The bottom of thechamber is covered in a pliable material 1303 to simulate soft tissuesthat may be contacted upon excessively deep insertion of the hollowneedle-thoracentesis needle. The elevated pressure within this chamber1300 is created when low pressure air from the combined pneumatic andblood simulant system see above is admitted. An alternate embodimentmakes use of a flexible lower layer 1303 of the chamber 1300 which isdriven by a linear actuator 1304, such that in the default state, thechamber 1300 volume is large, and upon generation of the tensionpneumothorax condition, the linear actuator 1304 pushes the flexiblelayer 1303 towards the costal body 1301, increasing the internalpressure. The tension pneumothorax section of the costal body 1301 isremovable. It consists structurally of a series of rib-shaped members1305, linked at their ends with a surrounding frame 1307. It is coveredon its outer surface with a skin-mimicking polymer material, and on theinner surface by an easily replaceable plastic membrane 1306. The edgesof the surrounding frame 1307 mate with a sealing lip 1308 that formspart of the main costal body 1202, 1203.

The hemothorax/pneumothorax chamber 1350 similarly comprises a removableouter section 1351 of the costal body, and an interior sealed space.Pneumothorax is achieved in the same way as the tension pneumothoraxchamber 1300, by the injection of air from the pneumatic and bloodsimulant system see above. Hemothorax is generated by the injection ofblood simulant. The schematic of FIG. 6 shows the arrangement of valvesand fluid pathways. As the forces generated during the chest walldissection and pleura puncture are much larger than for needlethoracentesis the plastic membrane 1352 is held between a fixed set ofinner half-rib shaped members 1353 that are part of the costal body1202, 1203, and a removable set of matching outer half-rib shapedmembers 1354. The outer set of ribs 1354 is similarly held together by asurrounding frame, is hinged 1355 at the sternal margin of the costalbody, and has a latching feature 1356 at the mid-axillary margin of thecostal body 1202, 1203.

In the case of both chambers 1300, 1350, water-resistant pressuresensors 1309, 1357 are installed to enable closed-loop control of thepneumothorax, hemothorax or tension pneumothorax states, such that therapid increase corresponding with tension pneumothorax or the slowerpressure increase of the other two conditions can be properly generated.

FIG. 14 shows an exemplary eye assembly unit 1400 including a base-frame1401 forming the back of the unit 1400 and support arms 1402 thatextends forward from it. To the support arms 1402 is mounted apitch-frame 1403 which pivots about an axis defined by the center pointsof each of the eyeballs 1404.

To the right end of the pitch-frame 1403 is mounted an R/C servo 1 405,with its rotational axis passing through the center point of the righteye 1404, and perpendicular to the plane of the pitch-frame 1403. Theright eyeball unit 1404 is mounted to the R/C servo output shaft 1405and to a bearing concentric with it below the R/C servo to providestability. A control arm 1406 extends backwards from the servo outputshaft behind the eyeball 1404.

The left end of the pitch-frame 1403 includes bearings to mount the lefteyeball unit 1404. The left eyeball unit 1404 includes a control arm1406 extending backwards from it's axis of the same length as the righteye control arm 1406. The control arms 1406 are connected to each otherby a rigid link such that when the right eye R/C servo 1405 turns theright eye 1404, the left eye 1404 turns through the same angle due tothe action of the connecting linkage (control arm 1406, rigid link,control arm 1406). This accomplishes the coupled yaw motion of the eyes.Depending on the choice of length of the rigid link, the eyes may gazein a perfectly parallel direction, or if slightly longer, may give theeyes a slight inward fixed vergence. The latter might give the user aslight sense that ACS is focusing on them, rather than to the distance.

The pitch-frame 1403 has mounted to it an R/C servo 1407 which may haveits rotational axis passing through the rotary axis of the pitch-frame1403, or it may be parallel but offset to it. In the former case, thisservo 1407 directly drives the pitch action of the pitch-frame 1403. Inthe latter, a series of gears or a toothed belt drive will transmit thetorque from the servo 1407 to the motion of the pitch-frame 1403. Thisaccomplishes the pitch motion of the eyes, moving in unison. Analternative design would mount the servo 1407 to the base-frame 1401,and through a gearing mechanism, with a gear section mounted to thepitch-frame 1403, would drive the pitch-frame 1403 about its axis.

The eyes are protected from contamination and damage by a sealed clearhousing 1408. The eyelids 1409 will be mounted outside of the housing1408 to provide manual access to them. The eyelids 1409 will be mountedabout the same axis as the pitch-frame 1403. A single servo, mounted tothe base-frame 1401, with its axis parallel to the eyelid axis controlsthe eyelid action.

One implementation that includes manual actuation of the eyelids 1409includes control arms extending up and down from the eyelid component atthe location of the rotary bearings. The upper and lower ends of thearms are attached to elastic cables would extend backwards from theeyelids 1409. They in turn are connected to control arms extending upand down from a shaft concentric with and mounted to the eyelid servo.As the servo rotates the upper control arm backwards, the eyelid opens,and vice versa. The presence of the elastic cables would permit a userto manually hold the eyes closed when otherwise in an open state, oropen when in a closed state. Upon release, the eyelids would return tothe state determined by the ACS consciousness level. The elastic cableswill also prevent damage to the servo due to excessively rapidback-driving, which could occur if there was a geared or beltedconnection between the servo and the eyelid components. Speed of eyelidmotion can be controlled by the rate of servo motion, and increasedfurther by selecting long servo control arms and short eyelid controlarms.

The range of motion of the eyelids 1409 will be limited by hard stops inthe skull/face unit. The eyelid servo will be commanded to open the eyesslightly beyond the open limit, and close beyond the closed limit. Inthis manner, there will be a slight preload (due to the elastic cables)that will prevent the eyelids 1409 from being free to oscillate (whichremains a possibility if the eyelids are commanded to an intermediateposition between open and closed). Suitable selection of bearingmaterials with some finite friction would minimize this, though caremust be taken so that the friction is not so high that the elastic cableforces are lower than the friction forces.

Ideally, the eye assembly 1400 is a self-contained unit that could beeasily replaced if damaged, rather than requiring disassembly ofexcessively large numbers of components from the ACS head.

FIGS. 15 and 16 show an illustrative overall layout of the ACS torsocomponents 1500, 1600. The ACS power systems, including the batterypacks 1501 and holder 1502 and the DC/DC power converters 1503, 1504 arearranged in the center of the ACS torso frame 1505. To either side ofthe battery packs 1501 are the high pressure air reservoirs 1506, which,in this embodiment, consist of a pair of 28 cubic inch air Pneuaire(Anaheim, Calif.) reservoir cartridges. Behind the reservoir cartridges1506 are the blood simulant containers 1507 (not shown are the pressurebags which surround them). Below the battery packs 1501 is the pair offluid flow sensors 1508, one each for IV flow measurement and bloodsimulant flow measurement. In the pelvic region is the pelvic frame1509, supporting the central processor 1510, the wireless network hub1511, and the GPS sensor 1512. Behind the pelvic frame 1509, 1601 andenclosed in a rigid shell (not shown) are the IV collection bags 1602and their associated pressure bags.

The animatronic components are made up of the flexible neck elements1513 and their associated air muscles 1514, the pan-tilt mechanism 1603(located within the skull housing 1604), the variable resistanceshoulder 1515 and hip joints 1516 (not shown are the SFE connectorswhich would be connected at the end of each of the short tube segments).In addition, the eye system 1517 and the jaw 1518 are actuated. FIG. 16shows more clearly the scapular elements 1605 of the shoulder mechanismand the fluid dampers 1606 attached to the lower margin of the scapulae1605 and the ACS torso frame 1607.

Not shown is the access door at the lower back which provides for theremoval and replacement of the battery packs 1501, 1608 and the bloodsimulant containers 1507, 1609.

Referring again to FIG. 6, in one embodiment, blood simulant is createdby injecting concentrated liquid colorant and thickener into one literbags of saline solution, which are then agitated to thoroughly mix thecomponents. These bags of blood simulant form the disposable (yetrefillable) simulant containers.

To install blood simulant containers, the simulator back panel isopened, exposing the two cavities in the torso that are occupied by onemodified pressure infusion bag 604 each (e.g. Ethox, Corp., Infu-surgpressure infuser bag). The simulant container 1507, 1609 is placedinside the pressure infusion bag 604, and the spike connector 1520, 1610is inserted through the main port of the simulant container 1507, 1609.

The pressure infusion bag 604 is connected to the low pressure circuitof the pneumatic system, described in FIG. 6.

During the priming sequence the pressure infusion bag 604 is pressurizedto approximately 4 psi, using pressurized air from the air cylinders601, 1506, regulated to 4 psi by the low pressure regulator 603. Thispressure is sufficient to generate arterial bleeding during uncontrolledhemorrhage simulation.

Under physiological conditions of reduced blood pressure, reduction ofbleeding flow rate and uncontrolled arterial spurting is achieved byreducing the duty cycle of open phase of the arterial flow valves 634(see FIG. 6). An alternate embodiment of the system achieves reducedapparent blood pressure by controllably changing the setting of the lowpressure regulator 603 through the use of a servo motor (of theradio-control type, however other servo motors are similarly suitable).A further alternate embodiment of the system achieves reduced apparentblood pressure by employing continuously variable analog valves (ratherthan binary on-off valves as the arterial flow valves 634), by reducingthe maximum opening of the valve during each pulse.

Upon removal and replacement of empty simulant containers 610, thesimulator back panel is opened, the spike connector 1520, 1610 removedfrom the empty container, and the container removed from the infusionpressure bag 604.

In another embodiment, blood simulant is contained within a pair ofrefillable cylinders containing a piston. At the upper end of thecylinder is a fitting that seals itself when disconnected from the restof the system, and another fitting with the same property is mounted atthe lower end. The piston, with seals around its circumference, can bedriven downwards by air pressure, pushing the blood simulant through thelower fitting. The lower end cap of the cylinder can be removed formaintenance and for refilling.

The air pressure applied to the cylinder is sufficient to generatearterial spurting from simulated arterial bleeders in suitably designedlimbs. Pulsatile flow is generated by controlling the opening andclosing of valves leading to the limbs in question. Reduction of flowrates corresponding with a reduction of blood pressure can be achievedeither by reducing the air pressure applied to the cylinder, or byrestricting the flow out of it using a suitable valve, or byindividually controlling the valves leading to the hemorrhaging limb(s)so that they do not open completely, thereby reducing the outflow. Inanother embodiment, the blood simulant cylinders will be easilyreplaceable from the mannequin, by making use of quick release fittingsand integrated retention systems, including the back panel of themannequin, which would also serve to hold the cylinders in place.

Each of the embodiments of the blood pressurization and containmentsystems is self-contained within the volume and anatomical constraintsof a nominal human form. Tubing would extend from either blood systemand transport pressurized blood simulant to each of the extremities.This would enable, for example, the torso to act as a full-featuredplatform even if the trauma modules connected do not require pulsatileflow.

FIGS. 17 and 18 show the full head-neck system 1700 of one embodiment.

The base plate 1701, 1801 is rigidly mounted to the thoracic componentsof the simulator skeleton 1802.

A serial chain of five universal joints (u-joints) 1702 connect thesimulator torso and head. The u-joints 1702 are of sufficient strengthsuch that the entire weight of the mannequin can be supported by any oneof them. The u-joints 1702, which are typically purchased as individualelements, are connected to each other by modifying them such that oneend forms a short rod and the other a mating hole (see FIG. 22). The rod2201 of one u-joint 1702 is inserted into the mating hole of the next2202, and a transverse pin 2203 of sufficient strength is removablyinserted into a transverse hole 2204 that passes through both therod-end 2201 and mating hole 2202. The transverse pin 2203 is mountedsuch that it can only be removed through deliberate action, and may be apress-fit pin, threaded element with suitable thread-locking material orother similar element.

Coincident with the mating location between adjacent u-joints 1702 ismounted a cervical disk element 2205. This element 2205 is mounted suchthat it cannot rotate about the longitudinal axis of the u-joints 1702.The cervical disk 2205 serves as the mounting element for an air muscleguide 1703, 2206, which can freely rotate about the axis of the cervicaldisk 2205. In this embodiment, the air muscle guides 1703, 2206 maintainthe alignment of the air muscles 1704, 1803 and the distance of the airmuscle 1704, 1803 from the axis of the u-joint chain 1702. In alternateembodiments employing cables or other flexible elements to providestiffness or animatronic motion, similar air muscle guides 1703, 2206would also be employed to maintain the geometric relations between thestiffening elements and the u-joint chain 1702.

Between each pair of cervical disks 2205 (or the last cervical disk 2205and the base-plate 1701, 1801) a pair of angle limiters 2207 is mountedco-axial with the u-joint 1702. The exposed surface of each anglelimiter 2207 has a geometry such that when the u-joint 1702 bends, itsmotion is limited by contact between exposed surfaces. The geometry ofthe exposed surface of the angle limiters 2207 is generated such that astraight line through the central joint of the u-joint 1702 iscoincident with the exposed surface, and that this straight linecorresponds with the desired angular limit of bending in a givendirection. For example, as shown in FIG. 21, the straight line throughthe sagittal plane 2101 of the joint has an angle of 3.75 degrees withrespect to horizontal, while the line through the coronal plane 2012 hasan angle of 5.625 degrees with respect to horizontal. These angles areselected such that the limits of motion of the full u-joint 1702/anglelimiter system 2207 are 45 degrees to either side in lateral flexion and30 degrees in both flexion and extension, which correspond to theapproximate ranges of motion of the human cervical spine.

At the top of the u-joint chain 1702 is a pan-tilt mechanism 2000 whichachieves the remaining motions of the head-neck system 1700, 1800,including an additional 30 degrees of flexion and extension and the full80 degrees in rotation to both the left and right. The pan-tiltmechanism 2000 is described further below. Of note here is the pan plate2001 of the pan-tilt mechanism 1900, 2000 which is mounted to theu-joint chain 2002 such that it can rotate about the axis of the chain2002, but can support the axial load of the weight of the simulator. Inthe current embodiment, an aircraft bearing, which can resist both largeradial loads and large axial loads, enables the motion of the pan plate2001. As the pan-tilt mechanism 2000 causes rotation of the head aboutthe u-joint chain 2002, the pan plate 2001 rotates with it. The 1704,1803, which are rigidly attached to the pan plate 2001 and the baseplate 1701, 1801, twist about the u-joint chain 2002, and the air muscleguides 1703, 2206, which can rotate with respect to the cervical disks2205, twist with them, while still maintaining the distance of the airmuscles 1704, 1803 from the chain axis.

Below the base plate 1701, 1801 are mounted the components to generatechanges in passive neck stiffness. FIG. 18 shows a lead screw 1705, 1804and a push plate 1706, 1805, which includes a threaded element 1707 thatmates with the lead screw 1705, 1804. The lead screw 1705, 1804 isdriven by the neck stiffness motor 1806 via a pair of spur gears 1807.Alternatively, the lead screw 1705, 1804 could be replaced by aball-screw system, and the spur gears 1807 could be replaced by a beltdrive, cable drive or other transmission, or the neck stiffness motor1806 could be coupled coaxially with the lead screw 1705, 1804. In thisembodiment, the transmission is employed as space for a coaxialarrangement is not available in the simulator torso. To the push plate1706, 1805 are mounted a pair of stiffening rods 1708 which are alignedparallel to the lead screw 1705, 1804. When the stiffening rods 1708 areat the fully retracted position, the u-joint chain 1702 can be freelymoved up to the limits imposed by the angle limiters 2207 and thepan-tilt mechanism 1900. When the neck stiffness motor 1806 turns thelead screw 1705, 1804 to move the stiffening rods 1708 into the extendedposition, the stiffening rods 1708 pass through holes in each of thecervical disks 2205. When extended, the u-joints 1702 can still bend,but the bending motion is resisted by the stiffening rods 1708. Thisgenerates a response similar the difference between an unconsciouspatient's neck which is completely limp, and a conscious patient's neckwhich can support the weight of the head or resist externally imposedmotions. To ensure that the stiffening rods 1708 pass through thematching holes in the cervical disks 2205, the rods 1708 pass throughguide tubes 1709, 1808 which are flexible, low friction tubes that areresident within the cervical disk holes 2205. The guide tubes 1709, 1808are rigidly connected to the pan plate 2001 of the pan-tilt mechanism1900, 2000, and are free to slide relative to the cervical disks 2205and base plate 1701, 1801 as the u-joint chain 1702 flexes. The guidetubes 1709, 1808 are long enough so that they extend below the level ofthe base plate 1701, 1801 regardless of the motion of the u-joint chain1702

FIG. 17 shows an exemplary embodiment of the animatronics of thehead-neck system 1700. The passive structural elements of the system aredescribed above, including the chain of universal joints 1702, thecervical disks 2205 and air muscle guide 1703, 2206, as well as theranges of motion of these components.

The neck motion is generated by the coordinated inflation of the airmuscles 1704, 1803 and release of air from them. McKibben type airmuscles are well known in the art, and detailed descriptions of theirmanufacture and function can be found in such references as Daerden&Lefeber. In essence, they comprise an elastic tube surrounded by ahelically wound mesh, in which the tube is typically sealed at one end,and attached to a source of pressurized air at the other. The mesh isbound to the tube at each end such that their lengths are keptidentical. As pressurized air is introduced into the air muscle, thetube expands, causing the diameter of the helical mesh to expand withit. As the mesh diameter increases, the helix angle of the inextensiblefibers within it decreases, causing the overall length to decrease. Whenone end of the air muscle is fixed and the other attached to a load,inflation of the muscle results in a force being exerted on the load ina direction towards and coaxial with the air muscle.

In the present embodiment, the neck actuation is enabled by antagonisticpairs of air muscles 1704, 1803, with one pair generating forces in theflexion/lateral right to extension/lateral left direction, and the otherpair generating forces in the flexion/lateral left to extension/lateralright direction. As one muscle of the pair is inflated, the other iseither held at current pressure or air is released. If both areinflated, this has the effect of stiffening the neck, and any differencein pressure results in motion towards the air muscle 1704, 1803 athigher pressure. By controlling the pressure in all four air muscles1704, 1803, any combination of motions in flexion/extension and lateralflexion can be achieved.

Air muscles in general can achieve an engineering strain (ratio ofmaximum change in length to original length) of approximately 25%. Forthis reason, the geometry of the air muscle guides 1703, 2206 and thelength of the chain of u-joints 1702 must be calculated such that thedifference in length between, for example, the front left air muscle1704, 1803 at full range extension and right lateral motion, and thelength of the same air muscle 1704, 1803 full flexion and left lateralmotion, is no more than the 25% of the full extension/right lateral airmuscle length. In short, the strain capability of the air muscle must bematched to the change in length imposed by the full range of motion ofthe neck.

Alternate actuators to air muscles can include variations in air muscledesign, the use of lead or ball screw mechanisms driving flexiblecables, or a pulley system driving cables looping from an attachmentpoint on the pan plate 2001, down the neck, under the base plate 1701,1801, around a motor driven pulley, and up the other side of the neck toreattach at the pan plate 2001. This is by no means a comprehensive listof design solutions, but is intended to indicate some of the possiblevariations.

In particular, to generate neck flexion, the front two air muscles 1704,1803 are pressurized, and air is exhausted from the back two air muscles1704, 1803, or the pressure therein is reduced with respect to thepressure in the front pair.

At the top of the neck section is the pan-tile mechanism 1900, 2000,which generates the rotational and part of the flexion-extension motionof the head. Pan motion (rotation) is achieved in this embodimentthrough the action of the pan motor 1903, 2003 with a gearhead ifnecessary to achieve the necessary torque, driving a pan capstan 1904,2004 around which is wound the pan cable 1905, 2005. This cable passesover a series of pulleys as shown in FIG. 20, and is anchored to the pandrive wheel 1906, 2006 using a cable stop and a cable tensioner 2007.The pan drive wheel 1906, 2006 is rigidly fixed to the uppermost u-joint1902, 2002. As the pan motor 1903, 2003 generates torque, this istransmitted through the pan cable 1905, 2005 to act on the pan drivewheel 1906, 2006. As the pan plate 2001 and tilt plate 1908, 2008 aremounted to the u-joint 1902, 2002 with rotary bearings, a torque equalto and opposite to that imposed on the pan drive wheel 1906, 2006 isimposed on the rest of the pan-tile mechanism 1900, 2000, causing it torotate about the u-joints 1702. Similarly, tilt motion is achieve astorque from the tilt motor 1909, 2009 (and possible gearhead) istransmitted through the tilt cable 1910, 2010 to the tilt drive wheel1911, 2011, and the tilt plate 1908, 2008 then tilts with respect to thetilt drive wheel 1911, 2011.

Closed loop control of the pan and tilt motions is achieved through theuse of encoders 1916, 2016 or similar sensors mounted on the motors, andalso from the pan potentiometer 1912 and tile potentiometer 1913, 2013,mounted between the tilt plate 1908, 2008 and uppermost end of theu-joint 1902, 2002, and between the right side plate 2014 and the righttilt shaft 1915, 2015 (which is fixed with respect to the pan plate2001). The potentiometers provide absolute position sensing of pan andtilt, and are used to determine the initial position of the pan-tilemechanism 1900, 2000 at simulator start-up, while the encoders 1916,2016 are used by the electronic motor control system to providenoise-free relative motion information, after the control system isinitialized with information from the potentiometers.

Closed loop control enables both control of the rotation andflexion/extension motions, but also enables control of the stiffness ofthose joints. For example, if simple position control is employed,increasing the control system gain which relates output torque of themotors to error between commanded and actual position, will increase thestiffness of the neck system (provided that friction in the joints andimposed by external soft tissue components and bandwidth of the controlsystem are sufficient to prevent control system instability). Othercontrol algorithms can also be employed to achieve the desired stiffnessand motion performance.

FIG. 23 shows components of the passive shoulder mechanism. This frontview shows the sternal plate 2301 (which forms part of the chest wallmotion/CPR system, described above) in the center. The clavicularmembers 2302 extend to the left and the right from tie-rod end joints2303 that allow limited motion of these members 2302. The clavicularmembers 2302 are rigidly attached to the scapular members 2304. Thescapular members 2304 include the sockets of the ball-joint mechanism2305 described below. The proximal margins of the scapular members 2304are connected to each other by a linear fluid damper 2306. Additionalfluid dampers 2306 connect the lower margins of the scapular members2304 and attachment points on the ACS torso frame. The fluid dampers2306 may be pre-tuned to provide fixed resistance to motion, or can havesmall servomotors attached to their adjustment points to enable activelytuned responses (similar to those of the shoulder, hip and head/neckjoints).

In one embodiment of the spherical joint mechanism employed at each ofthe hip and shoulder locations (see FIG. 24), the joint comprises theball assembly 2401, the socket assembly 2402, and the brake assembly2403. In operation, the externally threaded brake assembly 2403 isrotated by a motor or other means, and as a result of the threadspresses the ball assembly 2401 against a mating surface in the socketassembly 2402. With sufficient torque applied to the brake assembly2403, the ball assembly 2401 is rendered resistant to motion, which isthe desired state when the ACS is in conscious mode. Applying a torqueto the brake assembly 2403 in the opposite sense releases the ballassembly 2401, allowing the joint to move freely, which is the desiredstate when the ACS is in unconscious mode.

The ball assembly 2401 is comprised of a spherical ball with acylindrical member extending out from the center of the sphere. Thecylindrical member and the spherical ball may optionally have a holeextending through their common axis (see FIG. 24) to allow the passageof tubes or cables or other elements, such that those elements passthrough the joint, rather than needing to be channeled around theoutside of the joint. The advantage of passing such elements through thejoint is that additional cabling or tubing length is not required toallow the full range of motion of the joint, and reduces the possibilityof tangling.

The socket assembly 2402 is comprised of a hollow cylindrical body withan interior spherical seating surface at the outer end of thecylindrical body. The ball assembly 2401 rests in this seat with thecylindrical member extending out through the outer end. In the casewhere water resistance is a desirable feature in the ACS (as in thepreferred embodiment), an O-ring seat and an O-ring 2404 may beintegrated into the spherical seating surface such that a seal isestablished between the socket assembly 2402 and the ball assembly 2401.In addition to the spherical seating surface, an additional O-ring seatand O-ring 2404 are incorporated adjacent to and proximal from thespherical seating surface. Proximal to that is an internally threadedsection of the socket assembly 2402. This thread is provided to matewith the brake assembly 2403.

The brake assembly 2403 is a cylindrical element with a threaded outersurface to mate with the inner thread of the socket assembly 2402, and aspherical seat at its proximal end to mate with the ball assembly 2401's proximal aspect. As with the ball assembly 2401, the brake assembly2403 may have a hole extending through it to permit cables, wires orother elements passing through the ball assembly 2401 to enter the torsoof the ACS. To the inner face of the brake assembly 2403 is mounted aring gear 2405 with internal teeth. A pinion gear 2406 driven by a motor2407 causes the brake assembly 2403 to either move distally, squeezingthe ball assembly 2401 against the seat of the socket assembly 2402, orproximally, releasing the braking force.

In the shoulder joint 1515, the motor 2407 is mounted in a housing thatforms part of the scapular element 2408. In the hip joint 1516, themotor is mounted in the pelvic assembly 1519, which also incorporatesthe hip joint socket assembly 1516.

The use of a threaded connection between the brake assembly 2403 and thesocket assembly 2402 results in a non-back-drivable braking system, suchthat power is only supplied to the motor during the transition betweenstates. At all other times, the joint maintains its own state due tofriction. This minimizes the power requirements for the joint.

Alternate embodiments to accomplish the functions of the shoulder andhip joints described above can include a thread-less brake assembly 2403driven by a pneumatic cylinder, a solenoid or other linear actuator, asystem making use of a wedge that contacts an inner surface of the brakeassembly 2403 that pushes it against the ball assembly 2401 (as in aphotographic tripod bogen head), or other systems that may be conceivedby one skilled in the art. Similarly, alternate rotary actuators can beemployed to replace the motor 2407 described in the preferredembodiment.

FIG. 25 shows one embodiment of a replaceable battery pack for thesimulator comprising two sets of rechargeable cells 2501.

Each set of rechargeable cells 2501 is an arrangement of seven cellselectrically in series, providing a nominal output voltage of 23.1 V,rated at 2.3 Ah. Flat conductors 2502 are welded between successivecells to provide the electrical connection. Two sets of cells arestacked vertically, separated by an insulating structure mid-pack insert2503. Each set is connected via 18 gage (or similar) wire to a waterresistant connector 2504, one at each end of the battery pack 2500.

Structural rigidity is provided by the arrangement of the aluminum baseplate 1701, 1801, insulating plastic base insert 2505, a set of aluminumspacer rods 2506, the mid-pack insert 2503, an additional set ofaluminum spacer rods 2506, a connector 2504 holder, and finally theinsulating top insert 2507 and aluminum top plate 2508. The battery pack2500 components are held together with machine screws. The waterresistant connectors 2504 are held in place through the use of an epoxyadhesive or similar potting/bonding material, and the entire batterypack 2500 is coated in a continuous layer of waterproof plastic orrubber material, with the exception of the contact points within theconnector 2504.

Alternate embodiments of the power system include the use of single setsof rechargeable cells (rather than the dual set described above), theuse of a rigid waterproof shell (e.g. an injection molded part) ratherthan the system of separate structural and insulating members described,and other variations which may be found in similar replaceable powersystems that exist in the prior art.

The battery packs 2500 will be held within the simulator by a hingedpanel in the back of the simulator, which similarly restrains the bloodsimulant containers 1507, 1609. FIG. 25 shows a preferred embodiment ofa recharging system 2550 for the simulator's battery packs 2500. Thisembodiment supports the charging of four battery packs 2500simultaneously. One skilled in the art can easily conceive of variationsto support the charging of more or fewer battery packs simultaneously.

It includes a water-resistant housing 2551, of a type similar tocommercial Pelican cases, with the commercial foam insert in the lid ofthe case. In the body of the housing 2551 is a thermoformed panel 2552which includes mating features to provide positive alignment for thebattery packs 2500 and water resistant connectors 2504 at appropriatelocations to mate with the connectors on the battery packs.

Adjacent to the sockets and mating features for the battery packs is anindicator panel which covers the charging circuitry, and includesindicator lights which show which battery packs 2500 are being chargedand approximate charge level for charging packs. In addition, the panel2552 includes a main power switch and power supply cables and storagespace for said cables. The power supply cables include at least plugs toconnect to 110 VAC power sources, and may include additional cables andconnectors to connect to 12 VDC or 24 VDC vehicular power supplies.

The charging circuitry includes safety systems that include currentlimiting controls to avoid drawing excessive current from the powersupply, internal cooling fans, temperature sensors to detect excessiveinternal temperatures (and reduce charging current or shut down thecharging system as necessary).

The panel 2552 includes an interlock switch which disables charging whenthe lid is closed, to prevent overheating.

The panel 2552 further includes ventilation ports which are shielded toprevent water from splashing into the circuitry.

The panel 2552 further includes latches to retain each battery pack, anda spring-loaded ejection system to enable easy removal of the batterypacks 2500 from the recharging system 2550.

FIG. 26 illustrates the tactile buttons 2601 and dials 2602 on thecontrol panel 2600 which are intuitive to use and labeled to beself-explanatory. The use of stateless controls 2603 with separate LEDindicators 2604 to show their position enables the entire panel 2600 tobe reset electronically, or even remotely, without having to physicallyreset the switches.

It is understood that a wide variety of modifications and substitutionscan be made without departing from the present invention. In addition,while the invention is primarily shown and described in conjunction witha human mannequin, other embodiments are contemplated in which otheranimal forms are used for veterinary training for example. Nominal formfactors can be provided for horses, dogs, and other animals and pets.

While the invention is shown and described in conjunction with aparticular embodiment having an illustrative architecture having certaincomponents in a given order, it is understood that other embodimentswell within the scope of the invention are contemplated having more andfewer components, having different types of components, and beingcoupled in various arrangements. Such embodiments will be readilyapparent to one of ordinary skill in the art. All documents cited hereinare incorporated herein by reference.

1. A medical training system, comprising: a human mannequin; a centralprocessor in the mannequin, the processor being configured to receiveinput; a multidimensional lookup table stored in a memory, themultidimensional lookup table relating inputs from a plurality ofsensors to outputs including cardinal physiological status values; aphysiological modeling system coupled to the central processor tocontrol physiological responses of the training system for simulatingresponses of a human to trauma, wherein the physiological modelingsystem includes a plurality of effectors, and the central processor isconfigured to: determine a current physiological state using a selectedtrauma sequence, and a time duration since an initiation of the selectedtrauma sequence, receive an input value from at least one of theplurality of sensors, interpret the input value using themultidimensional lookup table to determine a new physiological state,and use at least one of the plurality of effectors to generate aphysiological response, wherein the physiological response is at leastpartially determined by the new physiological state and includes atleast one of clenching a jaw of the human mannequin, modifying a tone ofa muscle of the human mannequin, simulating signs of a tonic-clonicseizure, and rolling back a pair of eyes of the human mannequin; andwherein the human mannequin includes a support structure correspondingto a human skeleton, wherein the support structure articulates at jointsincluding neck, cervical spine, lumbar spine, shoulders, elbows, wrists,hips, knees, and ankles, wherein the central processor is configured tomodify a resistance of at least one of the joints of the supportstructure based upon the new physiological state.
 2. The systemaccording to claim 1, wherein the system is self-contained within themannequin.
 3. The system according to claim 1, wherein the system canoperate autonomously outside of the line-of-sight of an operator orinstructor.
 4. The system according to claim 1, wherein the input valuefrom the at least one of the plurality of sensors includes a total bloodvolume, an administered intravenous fluid volume, or a bronchial airflow rate.
 5. The system according to claim 1, wherein the physiologicalresponse includes at least one of modifying a heart rate and modifying ablood pressure.
 6. The system according to claim 1, wherein themultidimensional lookup table includes a representation of a nonlinearphysiological system behavior.
 7. The system according to claim 1,wherein the physiological modeling system includes a pulmonary system togenerate clinical signs for enabling diagnosis of hemothorax, tensionpneumothorax, or collapsed lung.
 8. The system according to claim 1,wherein the mannequin simulates unconscious and conscious states.
 9. Thesystem according to claim 1, wherein the neck joint includes at leastone stiffening rod, the at least one stiffening rod being selectivelyinsertable through at least one cervical disk connected to the neckjoint to control a stiffness of the neck joint.
 10. The system accordingto claim 9, wherein the neck joint includes at least two air muscles,and a movement of the neck joint is achieved by selectively actuating atleast one of the at least two air muscles.
 11. The system according toclaim 1, wherein the physiological modeling system includes a hemorrhagesystem configured to simulate pulsatile arterial blood flow, bone marrowseepage, or soft tissue bleeding.
 12. The system according to claim 1,wherein the plurality of sensors includes a sensor to measure fluidinput from a intravenous fluid input.
 13. The system according to claim12, further including a module to determine hemodilution.
 14. The systemaccording to claim 1, wherein the physiological responses includes vitalsigns including heart rate, heart rhythm, respiratory rate, respiratorydepth, systolic blood pressure, diastolic blood pressure, and level ofconsciousness.
 15. The system according to claim 1, further includingmedic RF-ID capability, GPS coordinate functionality, and time-of-daystamping.
 16. The system according to claim 1, wherein the physiologicalmodeling system includes a venous system configured to receive anintravenous (IV) fluid to which the system responds based upon theamount or type of IV fluid.
 17. A medical training system, comprising: ahuman mannequin including a support structure corresponding to a humanskeleton; a central processor in the mannequin, the processor beingconfigured to receive input from a plurality of sensors; a physiologicalmodeling system coupled to the central processor to controlphysiological responses of the training system, the physiologicalmodeling system being configured to: determine a current physiologicalstate, receive an input value from at least one of the plurality ofsensors, interpret an input value from a sensor to determine a newphysiological state, and modify a resistance of at least one of aplurality of joints of the support structure based upon the newphysiological state to simulate at least one of a generalized seizureand body stiffening.
 18. The system according to claim 17, wherein thesupport structure includes a neck joint, and the neck joint includes atleast one stiffening rod, the at least one stiffening rod beingselectively insertable through at least one cervical disk connected tothe neck joint to control a stiffness of the neck joint.
 19. The systemaccording to claim 17, wherein the support structure includes a neckjoint, and the neck joint includes at least two air muscles, and amovement of the neck joint is achieved by selectively actuating at leastone of the at least two air muscles.
 20. A method of providing medicaltraining using a human mannequin, comprising: determining a currentphysiological state using a selected trauma sequence, and a timeduration since an initiation of the selected trauma sequence; receivingan input value from at least one of a plurality of sensors connected tothe human mannequin; interpreting the input value using amultidimensional lookup table to determine a new physiological state,the multidimensional lookup table relating inputs from a plurality ofsensors to outputs including cardinal physiological status values; andusing at least one of the plurality of effectors connected to the humanmannequin to generate a physiological response, wherein thephysiological response is at least partially determined by the newphysiological state.
 21. The method of claim 20, including modifying aresistance of at least one of a plurality of joints of a supportstructure of the human mannequin based upon the new physiological state.22. The system according to claim 1, further comprising an integratedteaching system coupled to the physiological modeling system, whereinthe integrated teaching system is configured to: receive thephysiological responses and the inputs from the plurality of sensors;and determine whether appropriate medical interventions are beingperformed by an operator interacting with the human mannequin based onthe physiological responses and the inputs from the plurality ofsensors.
 23. The system according to claim 22, wherein the integratedteaching system is further configured to provide performance feedbackand teaching content to the operator.
 24. The system according to claim23, wherein the integrated teaching system is further configured tomodify the selected trauma sequence and the performance feedback basedon a skill level of the operator.
 25. The system according to claim 24,wherein the integrated teaching system is further configured todetermine the skill level of the operator by receiving data from anidentification tag carried by the operator.